1997 142th.
Greber Urs F	Viruses as parasites and gene transfer vehicles into cells.	3-12. (1)
	Viruses emerge randomly but frequently among the human population. Successful viruses are able to infect a large number of individuals. These viruses have learnt to exploit cellular mechanisms to enter their host cells and escape the host's immune surveillance. Type C adenovirus, a human cold virus, aims at delivering its DNA genome into the nucleus of epithelial cells in the respiratory tract. It enters target cells by receptor-mediated endocytosis, penetrates the endosomal membrane and is transported to the cell nucleus. It attaches to nuclear pore complexes and then disassembles and releases its genome into the nucleus. What are the molecular mechanisms which control this finely tuned entry and disassembly program?
Bandtlow Christine E	How nerve fibers find their targets.	13-21. (1)
	Neuronal growth cones traverse long distances along appropriate pathways to find their correct targets. Secreted and cell surface molecules in the growth cone's surface, trigger second messenger signals, and lead to appropriate steering decisions. Growth cones appear to be guided by at least four different mechanisms: contact-mediated attraction, chemoattraction, contact-mediated inhibition, and chemorepulsion. These mechanisms are mediated by different families of guidance molecules, including neural cell adhesion molecules of the immunoglobulin superfamily, netrins, and membrane bound inhibitors such as RAGS, all of which appear to be highly specific in their activity on certain growth cones. We are just beginning to gain insights into the function of these and other molecules in the developing and regenerating nervous system.
Mensch Roland, Känel Barbara, Uehlinger Urs	Short-term effects of weed removal on a stream of the Swiss plateau.	23-31. (1)
	In May and June 1995, we studied the short-term effects of macrophyte removal in a nutrient rich stream on macroinvertebrates and ecosystem metabolism. Following removal of macrophytes, water depth decreased by more than 50% and flow velocity doubled. Macroinvertebrate density was reduced by 65% after macrophyte removal. Chironomids and Simuliids were most affected because macrophytes are important habitats for these taxa. Asellus and Gammarus decreased after the removal of the plants presumable due to changed hydraulic conditions. Primary production was reduced by more than 50% after the removal of macrophytes. Community respiration, as well as respiration at the sediment surface, were little affected. Macroinvertebrates and macrophytes showed no recovery within 4 weeks after the disturbance, whereas primary production recovered within 4 weeks.
Gassmann Fritz	Complex systems: The combination of chaos and order.	41-48. (2)
	During the last two decades, new perceptions grew within the exact natural sciences relativating basic notions such as determinism and predictability of macroscopic phenomena. The result was a surprising opening towards life phenomena giving much hope for the possibility of a physical understanding of biology. The basic notions of chaos and self-organization are introduced from a historical point of view and then illustrated with a water wheel as a model system. On the basis of this system, we report also a new discovery concerning noise-induced chaos-order transitions. Finally, some questions are raised towards the calculability of natural systems and the possible physical understanding of life.
Simon Hans Uwe	The physiological and pathophysiological impact of programmed cell death.	49-53. (2)
	During the past few years, some progress has been made in understanding the control and mechanisms of programmed cell death (PCD). Nevertheless, major aspects remain undefined. However due to the availability of several important genes which play a role in the regulation of apoptosis, it should be possible to identify further proteins involved in this process. In addition to defining the molecular mechanisms of PCD, one should define the survival factors and the receptors for these factors for every cell type. Besides basic research, it is important to study the role and regulation of PCD in disease. Such clinical research will not only lead to more pathophysiological insights into diseases, but may also facilitate the design of new drugs to normalize dysregulated PCD. This review gives an introduction into our current understanding of both the physiological and pathophysiological role of PCD in humans.
Leu Urs B	History of dinosaur-research.	55-67. (2)
	There follows a description of the history of the reconstruction of the dinosaurs with reference to some rare documents preserved in the Paleontological Museum and the Central Library in Zurich. The history of Swiss research is also discussed as well as the first report of Swiss dinosaurs which has been published in 1824. Because the ichthyosaurs and pterosaurs are often commonly associated with the dinosaurs, they are also subjects of this paper.
Brinkmann Winand	Ichthyosaurs (Reptilia) from the Middle Triassic of Monte San Giorgio (Ticino, Switzerland) and Besano (Lombardy, Italy): The present state of research.	69-78. (2)
	Middle Triassic marine sedimentary layers (Grenzbitumenzone, Lower Meride Limestone, Kalkschieferzone) from the Ticino calcareous Alps at the Swiss-Italien border have long been recognized by specialists as a classical fossiliferous area (Monte San Giorgio/Besano), rich in exquisitely preserved fishes and especially many different kinds of marine reptiles, among them ichthyosaurs. Palaeontologists of the University of Zurich have been studying the abundant ichthyosaur material from that region in detail for some years. The aim of the paper is to give an overview of the present state of the research. The Ichthyosaurian fauna of the "Grenzbitumenzone" or Besano Formation of the Ticino calcareous Alps is very diverse. The fauna consists of individuals of the small mixosaurs Mixosaurus, which are very frequent, and Phalarodon, one specimen, as well as some larger shastasaurids, for example Besanosaurus and Cymbospondylus. The mixosaur material, including some remains of embryos of Mixosaurus, and an additional shastasaurid from Monte San Giorgio are currently being studied Here, for the first time, the occurrence of the genus Phalarodon in Southern Ticino and the respective conclusions are reported.
Hantke, René Adrian E. Scheidegger	Zur Morphogenese der Zürichseetalung	89-95, (3)
McKenzie Judith A, Andres Miriam S, Vasconcelos Crisogono	How do bacteria make rocks?	97-104.(3)
	An earth-system-science approach to the study of chemically produced sedimentary rocks is multidisciplinary, involving an integration of biology, chemistry and physics. With this approach, the study of rocks on a geological time scale is linked to processes observed in modern natural environments, which in turn provide material and models that can be tested in the laboratory. Studies of ancient rocks demonstrate that the interaction of bacteria with their environment has resulted in the precipitation of chemical sediments throughout geologic time, beginning with the oldest known sedimentary rocks from 3.5 Ga, whereas studies of modem environments provide information on the conditions prevailing in the geologic past. Dolomite precipitation is presented as an example of a chemical sediment that illustrates the influence of geomicrobial activity on the production of the rock dolomite throughout geologic time.
Lippuner Mario	Agile frog (Rana dalmatina Bonaparte, 1840) new for the cantons of Zurich and Thurgau.	105-113. (3)
	Rana dalmatina is described as a faunal element of the cantons of Zurich and Thurgau. In the mchlt Red List mchgt of Switzerland the species is listed as mchlt endangered mchgt north of the Alps. It has been known to occur in the canton Of Schaffhausen and in Southern Germany north of the River Rhine which has been regarded as the southern boundary of range. The fact that R. dalmatina-specific habitats exist south of the River Rhine in the neighbouring parts of the cantons of Zurich and Thurgau led the author to explore some wet-sites in this area in April 1996. He found R. dalmatina in two places: one in the community of Unterschlatt, canton of Thurgau, and one in the community of Trullikon, canton of Zurich. In spring 1997 further findings followed in 13 objects. In' the present report the records and the corresponding habitats are described. Comparison of the habitats with bibliographical references led to recommendations for the protection of R. dalmatina. Measuring the adults, of two different populations showed that males have an average head-trunk-length (AHTL) of 51.5 mm and 49.1 mm respectively and an average weight (AW) of 16.4 g and 15.7 g respectively. The corresponding values of the females were: AHTL = 62.8 mm and 62.1 mm respectively; AW = 34.2 g and 31.7 g respectively. Furthermore a morphological character distinguishing the larvae of R. dalmatina from R. temporaria is presented.
Braegger Christian P	Is there a need for basic research in clinical medicine? New immunosuppressive treatment strategies in Crohn's disease.	115-122. (3)
	Crohn's disease is a chronic inflammatory bowel disease of unknown etiology. During the last 20 years there has been a steady rise in the incidence and prevalence of the disease in Europe and the United States. The rise in the incidence is even greater in children. In more than 30% of the patients the disease begins during childhood. Treatment of Crohn's disease is often not effective enough and associated with many side effects. However recent findings in immunology and molecular biology provided new insights into the pathogenesis of the disease. New experimental approaches of immunosuppressive treatment are currently developed.
Martin A. Suhm	Aus dem Gesellschaftsleben eines kleinen Moleküls:Eine Einführung in die Molekularsoziologie	133-143, (4)
Jovan Pavlovic	Abwehrstrategien gegen Grippeviren Induktion antiviraler Mx-Proteine durch Interferon	145-152, (4)
Urs Boutellier	Auch die Atmung limitiert die körperliche Leistung bei gesunden Personen	153-159, (4)
Nazario Pavoni	Geologische Exkursion an die Lägern vor 160 Jahren	161-168, (4)
Nazario Pavoni	Diskussionsbeitrag zum Forum-Artikel "Zur Morphogenese des Zürichseetalung" von R.Hantke & A.E. Scheidegger	169-172, (4)

1996 141th.
Ruth Dreifuss	Ethik und Verantwortung in der Wissenschaft	3-7, (1)
J. Osterwalder	Atomare Struktur auf Katalysatoroberflächen	9-15, (1)
Opravil Milos	How do microorganisms profit from immune deficiency?	17-28. (1)
	In the course of evolution, microorganisms found different ways to escape the immune defence. One of the viral strategies is the introduction of their genetic information into chronically infected human cells, as shown for the herpes viruses and HIV Some bacteria or parasites can persist in the macrophages or in a cyst during the whole life without causing any symptoms. Frequent mutations and antigenic shift can additionally impair the recognition by the immune system. The cells of the immune system itself may also become infected which will directly or indirectly damage the immune defence. Immune deficiency will facilitate the establishment of an infection, even by microorganisms that are usually not pathogenic. Additionally, reactivations of latent infections occur frequently and lead to serious and chronic diseases. Without the adequate functioning of the immune system, antibiotic treatment alone will not be able to eliminate the microbes. Moreover, better conditions for the growth of microorganisms will promote the development of resistance with further impairment of the treatment effect.
Hilbrecht Heinz, Graf Pinthus Brigitte	3-D morphometry of palates with simple image analysis.	29-33. (1)
	A variety of methods exists for the medical treatment of cleft lips and palates, with a common goal to establish a normal geometry of the palate. Using x-ray absorption we transformed the three-dimensional height variation in gypsum casts of palates to a two-dimensional image, computed thicknesses of gypsum through correlation of gray values in the image with measured thicknesses, and measured the height variation along three lines across the palate with an image analysis system. One criterium to choose methods for image generation, image analysis, data evaluation, and presentation was to involve medical doctors without specialised experience in image analysis and morphometric data handling, who should be able to evaluate and to apply results based on their medical experience with the patients. Both analysed methods for the medical treatment of cleft lips and palates produce comparable results. One method, however, achieves its goal to cure the patients after significantly shorter time.
Nadal David	Epstein-Barr virus in tumor cells: Stowaway or helmsman?	45-52. (2)
	The specifically human Epstein-Barr virus (EBV), a member of the herpes virus family, has been discovered more than 20 years ago and can be found in certain tumors. This justifies the question whether it acts as causative agent. The primary infection is usually acquired in early life and may result in infectious mononucleosis. Despite targeted immune response the virus cannot be cleared from the organism. Approximately 95% of the adult human population harbours the EBV The main targets are the B lymphocytes in which the virus exhibits either lytic (productive) or latent infection. The latter confers to B lymphocytes increased potency to proliferate. In immunologically healthy individuals, the incited proliferation is confined by cytotoxic T lymphocytes. However the EBV may escape the attack by reduced expression or mutation of latency genes. The expressed gene patterns suggest that in tumors of immunocompetent individuals the EBV behaves as a stowaway or as a camouflaged saboteur. By contrast, there is no doubt that in tumors of immunocompromised persons the EBV acts as a helmsman.
Schuepp Hannes, Frey Beat	The complex and dynamic interactions between the arbuscular mycorrhizal fungi and the plants.	53-63. (2)
	Arbuscular mycorrhizas are an universal, mutually beneficial, symbiosis between plants and fungi. They are most common in almost all plant species in natural and agroecosystems. They form abundant internal structures within the roots and extensive external mycelia throughout the soil. Arbuscular mycorrhizal fungi act as a major interface between the plants and the biotic and abiotic components of the soil. The complex positive interactions of the symbiosis concerning nutrition and development of plants as well as the improving soil structure and enhancement of bioactivity has become only in recent years a topic of comprehensive, interdisciplinary research. Some results are presented concerning the dynamics of the biomass of the mycorrhizal fungi and their role in the nitrogen cycle mainly with regard to transport and availability of nitrogen.
Vogel Ralph Bernd, Egger Heinz, Schweingruber Fritz Hans	Interpretation of extreme tree ring values in Switzerland based on records of climate between 1525 and 1800 A.D.	65-76. (2)
	After the astronomer Andrew Ellicot Douglass succeded in dating the famous cliff-dwellings of Pueblo Bonito by means of wood remains, historians and archaeologists throughout the world began increasingly to include dating by tree rings in their research. In Europe the felling dates of thousands of trees were set in their historic context. Nevertheless, climatological interpretation was largely unsuccessful as the tree rings in wood remains from former settlements contained little information. However where extremely broad or narrow rings were observable it became possible to determine a relationship to extreme climatic events. By mapping of what are termed pointer values and intervals of climatically uniform Mittelland, it has proved possible, with the aid of climatic records, to recognise and explain years with extreme events, for instance years with very cold winters (e.g. 1624) and dry or wet summers (e.g. 1636 or 1673). In some years the dendrochronological data do not match the climatic records. Consequently it may be possible in future to supplement the data from climatic records with dendrochronological information.
Bucher Fritz	Rhinoceros protection: An example from Kenya.	77-80. (2)
	The survival of all rhinoceros species is endangered on a global scale, because the area of their habitats decreases and because they are killed for their horns. Even the formerly quite numerous African black rhinoceros with populations estimated in 1968 to still number 11 000 to 13 500 individuals has meanwhile been drastically reduced to about 2500 individuals. In many African countries it is by now extinct or close to extinction. Only in South Africa, Namibia, and Kenya the populations are stable or even increasing. Similar or worse reports concern the other rhinoceros species in, Africa aid Asia respectively. After a short historical survey on the rhinoceros slaughter in the 19th century the author analyzes the present situation and comes to the conclusion that the rhinoceros species have only a chance of survival when guarded in well watched surveyable and fence-protected sanctuaries. Important is that the native human population is included into the protection programme and profits from it. - As a specific example the Ngare Sergoi Rhino Sanctua in Lewa Downs (Kenya) is described in more detail.
Minder Elisabeth I, Schneider Yin X, Schäfer B, Rüfenacht U	Porphyrias in changing times: From biochemistry to gene therapy.	93-101. (3)
	Porphyrias are a group of inherited disorders of porphyrin metabolism. The main symptoms of porphyrias can be either repeated attacks of abdominal pain and psychotic symptoms, or a hypersensitivity to the sunlight Well-known dignitaries, who might have suffered from porphyrias, were Vincent van Gogh and King George III of England. The diagnosis of porphyrias can be established by increased levels of porphyrines in various body fluids. Defects in the enzymes of the heme-biosynthetic pathway are the causes of porphyrias. Many of these defects have been identified in the respective genes. In vitro substitution of the normal gene sequence by a defect one allows the study of the effect of this particular defect on the enzyme activity and the correlation with clinical expression. Since there is no effective therapy for most of the porphyrias, people focus their attention on the gene therapy research, ie. replacing the defect genes by normal ones that might bring a correction of the disorders and in turn cure the patients. Successful in vitro gene therapy experiments have shown promising results in two forms of porphyrias. However, there are still some obstacles to be overcome before applying gene therapy to patients.
Scheib Stefan	The Gamma Knife: Medical physics meets neurosurgery.	103-111. (3)
	The first and to date only Gamma Knife in Switzerland was installed at the "Klinik Im Park" in Zurich in September 1994. This treatment facility is designed to perform stereotactic radiosurgery of small intracranial tumours (both malignant and benign) and arterio-venous malformations. Stereotactic radiosurgery is a technique in which a single high dose of radiation is applied with an extremely high degree of spatial accuracy. The method can be used instead of or in addition to neurosurgery. The Gamma Knife uses 201 converging beams of 60cobalt radiation and this "crossfiring" technique gives a small sphere of high dose at the target lesion with sparing of the surrounding normal brain tissue. By positioning one or more such dose spots within the target lesion virtually any required 3-dimensional dose distribution can be produced, in order to cover the target volume with the required dose. To date over 42 000 patients have been treated with this technique at over 70 centers world wide. The complete treatment procedure last between about 3 and 8 hours and can be carried out either on an outpatient basis, or with a short stay in hospital.
Spichiger Keller Ursula E	How far do chemical sensors resemble sensillae?	113-122. (3)
	The structure of biological sense organs such as the antennulae of crabs or even simple taste or olfactory hair-sensillae of insects is complex and their supply with nutrients as well as their response functions are complex, too. The goal of developing chemical sensors is, however, to design sound, simple and efficacy tools to use in analytical chemistry. Chemical sensors in a strict sense are designed and realized based on synthetic host molecules. The environment of the host-guest interaction contributes significantly to the selectivity of this tool. Components of biological sense organs e.g. enzymes or other receptor molecules are used in chemical sensors in order to have access to the natural discrimination of interfering substances. Such sensors are specified as Biosensors. Common to all chemical sensors is their reversible or rapidly regenerable response to varying concentrations of "stimulating" molecules or target analytes. This feature allows to operate those sensors in continuous monitoring. The various types of chemical sensors can be described schematically by a common model involving, firstly, the section of molecular recognition; secondly, the transducing section where the molecular recognition process is translated into a physical quantity, and thirdly, a secretion responsible for signal processing and yield of information.
Urmi Edwin, Schnyder Norbert	A digital system of physiographic surface units in Switzerland and in Liechtenstein.	123-131. (3)
	The authors propose a digitalized system of physiographic units allowing to produce automatically bryophyte distribution maps. The units were generated to be comparable in size and to be as homogeneous as possible regarding geology and climate. The system was designed for ARC/INFO but it can be applied together with other geographical information systems. It consists of 413 physiographic units of Switzerland with an average surface of exactly 100 km-2 and of 2 smaller units of Liechtenstein. It proved useful for the purpose for which it was originally assigned with or without modifications, it is expected to facilitate the processing and the presentation of other geographical data, too.
Klaus Ensslin	Klassisches Chaos und Quantentransport: Experimente an Halbleiter-Nanostrukturen	146-152. (4)
Keller Beat	Traditional and molecular use of the biodiversity of wild grasses for wheat breeding.	153-160. (4)
	The improvement of disease resistance is one of the most important goals in wheat breeding. Many of the desired resistances against fungal and viral pathogens are not present in the wheat gene pool. However, such genes are often found in wild grasses which are related to wheat. It is possible to transfer resistance genes from a number of wild grasses into wheat by sexual crosses and cytogenetic methods. In these introgressions, large chromosomal fragments are transferred from the wild grasses into wheat. Besides the desired resistance gene, there is a large number of additional genes on these fragments which often result in undesired traits in modern wheat varieties. Therefore, only a small number of the useful traits present in the gene pool of wild grasses has been introduced into commercial wheat varieties. To use the genetic diversity of resistance genes of wild grasses to a larger extent in wheat breeding, the genes will have to be isolated with molecular methods to allow the separation from other genes of the wild grass. The progress in the characterisation of resistance genes in small grain cereals is briefly described for rice and wheat. In the next years, we can expect the isolation of a larger number of resistance genes from wheat and its related grasses.
Schlumpf Margret, Lichtensteiger Walter	Environmental endocrine disruptors: Their role in loss of animal species.	161-171. (4)
	The impressive loss of animal species in the 20th century is caused mainly by human activity. Of great concern is the yet unexplained accelerated decrease of animal species during the last 3 to 5 decades. Habitat degradation and chemical pollution are among the primary determinants contributing to this process. Numerous examples from plancton to humans document the relationship between chemical burden (organic chemicals and heavy metals) and impaired reproduction and development. However, at present it is not possible to assess the significance of a prolonged exposure to environmental chemicals, in particular because of insufficient information on toxic effects in the low dose range with long-lasting exposure (one generation or longer). Reproduction and ontogeny are highly sensitive to chemical insults, especially by chemicals known as endocrine disruptors, interacting with the regulation of physiological functions by hormones. In adults such interactions may interfere directly with reproduction; during critical phases of development they may lead to persistent changes in structure, biochemistry, and function of various organs including the reproductive organs. At the present time, we are faced with a discrepancy between the paucity of data on reproductive and developmental toxicology of environmental chemicals and the enormous number of bioaccumulating xenobiotics.
Jeanmonod Daniel, Magnin Michel, Morel Anne	Common thalamic physiopathology for sensory, motor, and limbic positive symptoms in man.	173-181. (4)
	Positive symptoms arise after lesions of the nervous system. They include neurogenic pain, tinnitus, abnormal movements, epilepsy and certain neuropsychiatric disorders. Stereotactic medial thalamotomies were performed on 104 patients with chronic, therapy resistant positive symptoms. Peroperative recordings of 2012 single units revealed an overwhelming unresponsiveness (915%) to sensory stimuli or motor activation. Among these unresponsive cells, 45% presented a bursting activity with a rhythm between 3 and 5 Hz. These bursts fulfilled the criteria for "low threshold calcium spike (LTS) bursts", which are strictly related to thalamic cell inhibition. These bursts were identical for all positive symptoms. Operations in the medial thalamus and in the pallidum allow a reduction or relief of the positive symptoms. On the basis of these electrophysiological and clinical results, we propose a unified concept for all positive symptoms, centered on a self perpetuating thalamic cell membrane hyperpolarization, similar to the one seen in slow wave sleep.

1995 140th.
Akeret Beat, Stössel Fred	Comparative ecological investigations in nine ponds north of Zurich (Switzerland).	3-17. (1)
	We measured temperature, conductivity and several chemical parameters in 9 ponds. We also investigated animal and plant diversity. The ponds ranged from regularly and thoroughly mixed to stratified. Concentrations of nutrients spanned a wide range. All ponds were at least partially anoxic, especially in summer - and even near the surface oxygen concentrations were low. Nevertheless, biodiversity was high in 7 of the 9 ponds. Overall, 192 taxa were found but only 1 species occurred in all ponds. 9% (18) were found in more than four ponds, 20% in two and 65% (124) only in one pond. Our study shows that each pond is unique and is therefore hardly comparable to other ponds.
Weibel Robert	Spatial data handling and digital terrain modelling.	19-29. (1)
	Digital terrain modelling allows to numerically model topographic relief and to simulate relief dependent processes. Here, we use digital terrain modelling as an example to illustrate the application opportunities and the potential of spatial data handling, an essential component of modern geographical research. Three central objectives of spatial data handling - information extraction, quantitative modelling of spatial processes, and visualization of complex spatial relations - are illustrated by application examples of terrain modelling. The corresponding methods are briefly described.
Hanggi Gaby, Felder Peter	Lasers in medicine.	31-34. (1)
	In the past few years, the continuous development of laser technology has led to remarkable progress in medical therapy and diagnostics. Lasers are used in surgery as localized heat sources to achieve tissue removal and coagulation of surrounding blood vessels. Photodynamic therapy is a tumor treatment modality in which laser light is applied to activate suitable photosensitisers. Shock waves generated by means of pulsed high power lasers are used for the destruction of various types of intracorporeal stones.
Krause Martin	Infectious diseases on the way: Molecular aspects of pathogenesis.	35-41. (1)
	First brief account on the history of infectious disease and the successful therapy by means of prevention and antibiotics is given. The growing problems caused by developing microbial resistance to antibiotics and the appearance of new infectious diseases as well as the reappearance of "old" infections require further intensive research. Over a long time the study of the pathogens was neglected in favor of the research on the immune system of the host and its signal substances. Today it is accepted that during infection the microbe is at least as important as the host and its defense lines. The terms "pathogenicity" and "virulence of the infecting agent" are discussed. Special attention is drawn to the pathogenesis of Vibrio cholerae (cholera toxin) with its disastrous effects, to salmonellae and the regulation of their virulence genes, and of Yersinia pestis with is adaptive mechanisms in response to the changing temperatures in the rat, in the rat-flea, and in humans.
Burg Jean Pierre	How many years can mountains exist before they disappear in the sea?	51-60. (2)
	The natural deformation of rocks tells the rheological response of crustal material to forces due to large movements between lithospheric plates. Geological structures also tell about the slow collapse of mountain ranges due to the applied on thick and hot, softened crusts. The subsequent vertical movements and topographic changes may force changes in the wind circulation and, therefore, in the global climate. In the lecture the unexpected relationship between internal and external geodynamic systems is developed and some records in the geological and climatic history of the Earth nearly 300 My ago are traced.
Hatt Jean Michel	Falcon and Cheetah: Man's hunting companions.	61-68. (2)
	For centuries man has used certain animals and birds to hunt prey where technical means of hunting were lacking. Countless sources testify to the intensive relationship which built up between man and beast beyond the initial need. In this article the history of hunting with the aid of cheetahs and falcons will be studied. Both traditions have been deeply influenced by the development of modern arms. The decrease in the cheetah population has led to the disappearance of this method of hunting. Falconry, however, fortunately has a good chance of survival in Europe due to great efforts of falconers in the protection of birds of prey and their environment.
Schmid Werner	Genetic mosaicism in man.	69-74. (2)
	Various kinds of genetic mosaicism are not only scientifically interesting phenomena but are of clinical relevance as well. This is particularly so for mutations occurring in the early embryo, for the mutations leading to cancerous cells, and for mosaicism in patients with chromosome aberrations. Random events in conjunction with the inactivation of one or the other X chromosome in female cells give rise to the occasional heterozygous woman who is clinically manifest for hemophilia or muscular dystrophy. Mosaicism is widespread among the newly discovered triplet repeat diseases, among them Huntington's chorea and myotonic dystrophy. Their triplet expansions are unstable not only meiotically but mitotically as well. Diseases caused by mutations or deletions in the mitochondrial chromosome can be compatible with life only in mosaic condition.
Sengstag Christian	Predisposition to colorectal cancer: Familial inheritance of mutant DNA repair genes.	75-82. (2)
	Recent research results confirm the hereditary nature of certain forms of colorectal cancer Systematic screening of individual members within cancer-prone families revealed four novel genes which are present in an altered state in affected family members. The newly identified genes hMSH2, hMLH1, hPMS1 and hPMS1 exhibit good similarity to known bacterial genes and they were identified to code for proteins which are involved in the recognition and repair of DNA mismatches. The observed alterations in the genes lead to a defect in the removal of spontaneous DNA damage, the consequence of which is the outbreak of cancer. This review describes the scientific route that has led to the identification of these four genes.
Ryffel Bernhard	Interleukin 12: Adjuvant in tumor therapy?	83-87. (2)
	Interleukin 12 (IL-12) is produced in the body by macrophages and B-lymphocytes in response to bacterial infections and intracellular parasites and establishes a link between natural defense mechanisms and acquired immunity. IL-12 stimulates the immune system, especially natural killer cells and cytotoxic T-lymphocytes, which play an important role against infections and tumor cell growth. The biological properties of IL-12 are briefly reviewed and the encouraging results from experimental cancer studies are presented. The potential application of IL-12 for cancer therapy in patients is discussed along with the expected adverse effects of such a therapy.
Hanggi Gabriella	Contrast agents for diagnostic imaging.	97-104. (3)
	Over the past twenty years the imaging techniques available for diagnostic use have experienced a rapid and impressive development. Traditional radiology was revolutionized with the advent of digital recording technology and associated computer analysis. In addition to x-ray tomography, novel diagnostic imaging methods based on entirely different physical principles, such as ultrasonography and magnetic resonance imaging, have been introduced. By appropriate use of these techniques detailed visualization of pathological alterations in the human body can be achieved. However, this is not only due to progress in instrumentation, but also to the development of suitable contrast agents. For x-ray imaging, several well tolerated iodine-containing contrast agents are now available, thus providing a wide application range. For contrast enhancement in ultrasonography, a product based on microscopic air bubbles has been developed which, however, is currently limited to the use in cardiology. Paramagnetic gadolinium complexes are well established in magnetic resonance imaging for a sensitive detection of tumors and metastases in the brain and in soft tissue. Superparamagnetic magnetite particles show selective accumulation in healthy liver tissue and thereby permit an earlier and more reliable diagnosis of liver tumors.
Hansjörg Seiler	Umweltrisiken als Gegenstand interdisziplinärer Risikoforschung	105-112 (3)
Wilfried Haeberli	Permafrost und Blockgletscher in den Alpen	113-121 (3)
Gmur Rudolf	Aggressive opportunistic bacteria and a deregulated immune response: Triggers of periodontitis.	123-131. (3)
	Periodontitis is caused by a destructive inflammation of the tissues which, as a functional unit, anchor the teeth. Prerequisite for the disease is the colonization of the teeth and in particular the gingival crevice with aggressive opportunistic bacteria. Certain substances from the bacterial flora are directly toxic to host cells, others are capable to strongly stimulate the local immune response which may result in immunopathological tissue destruction. In general, periodontal bacteria alone seem not to be able to cause periodontitis as long as polymorphonuclear granulocytes are present and functional. If the bacteria succeed in outflanking or eliminating the phagocytes (rarely the case) severe periodontitis is an immediate consequence. Much more often, a basically sound by chronically overstimulated local immune defense is associated with periodontitis. In such cases, a critical change in the cytokine profile, presumably caused by external or other destabilizing factors (smoking, drugs, age, diabetes, stress, etc.), may be essential in triggering a burst of periodontitis.
Pellegrini Antonio	Lysozyme: An old protein keeps the interest of research constantly awake.	133-140. (3)
	Since its discovery by Alexander Fleming 70 years ago, lysozyme has attracted the attention of a large number of biological and medical scientists. Because of the greater antibacterial activity of penicillin, lysozyme was neglected for 30 years. However, starting in 1960 a revival took place; lysozyme became the first enzyme whose molecular structure was completely analyzed. Recently it has been shown that the bactericidal activity of lysozyme is independent of its enzymatic activity. The finding that a pentadecapeptide derived from the enzymatic digestion of lysozyme shows antibacterial and antiviral activity is new.
Arnold O. Benz	Koronen: Heisse Hüllen kühler Sterne	149-153 (4)
Billeter Martin	Water molecules within and around proteins.	155-161. (4)
	Proteins participate in almost all biological processes; they thus affect many properties of living organisms. The multitude of protein functions is made possible by an even larger multitude of three-dimensional protein structures. The function of a protein depends on direct contacts to other molecules; therefore protein functions are strongly correlated to protein surface structures. The study of interactions of proteins with their environment requires the consideration of neighboring water molecules. Different experimental techniques (X-ray crystallography, NMR) show different aspects of protein-water interactions. By combining these results a model emerges, in which water does not simply fill the space between larger molecules but also enables fluctuating interaction networks between proteins and other molecules with the resulting entropic advantages. Complexes of proteins with DNA, where the proteins "read" the genetic information of the DNA, illustrate this model.
Leuthold Walter	Changes of the vegetation in the Tsavo National Park, Kenya, From 1970 to 1994.	163-171. (4)
	Two series of photographs taken at spatially fixed locations in 1970 and 1994 document the development of woody vegetation under changing ecological conditions in Tsavo National Park. Kenya, over nearly a quarter-century. The original vegetation was altered considerably through the combined influences of elephants and fire in the 1950s and 1960s. Meanwhile, the elephant population has decreased substantially as a result of large-scale poaching for ivory during the 1980s. Presumably as a result, trees and shrubs have reappeared in large numbers at the majority of locations sampled. The influence of fire in impeding regeneration of woody vegetation has also been documented locally.
Schmid Christoph	Insulin-like growth factor: Hormone and cytokine.	173-180. (4)
	Insulin-like growth factors (IGFs) were discovered by three independent groups interested in biological activities exerted by serum: stimulation of proteoglycan synthesis (sulfate incorporation) in cartilage by a growth hormone-dependent "sulfation factor" (somatomedin), insulin-like activity (non-suppressible by anti-insulin antibodies, NSILA) on adipose tissue and mitogenic activity on fibroblasts in vitro (multiplication-stimulating activity). IGF I works as a somatomedin in animals and in man. It is currently being tested in patients with diabetes mellitus. Apart from its functioning as a blood-borne, liver-derived endocrine hormone, it is produced in most tissues where it contributes to tissue growth, repair, and remodeling (e.g. of bone) in a paracrine/autocrine fashion.
Rüetschi Bernhard	Environmental pollutants and allergies.	181-184. (4)
	With our present lifestyle, we come into contact with an increasing number of substances which irritate the skin and the mucous membranes, affecting the barrier function within the respiratory passages and leading to increased susceptibility to infectious diseases or allergens. Hence the number of allergic reactions world-wide has increased over the past few years. New studies indicate that the interaction of a number of factors is responsible for causing illness, in particular for the increase of allergic reactions. For example, allergies are more likely to arise in highly polluted areas. the coexistence and simultaneous effect of environmental pollutants, allergens,a nd infectious agents can cause latent allergies to develop. Smoking, active and passive, can also contribute to the development of allergies. Multiplex interactions are often encountered when tracing the cause of illness within a household. There, one person can be completely healthy, while another is sensitive to irritants, and yet another shows symptoms of an allergy. Most toxic and allergic illnesses are polycausal and therefore difficult to understand and explain. A diagnosis including detection of the damaging substances or allergens and appropriate treatment is in many cases not possible. therefore, preventive measures, especially the maximum possible elimination of noxious substances, should have first priory.

1994 139th.
Jetzer, P.	Gravitational lenses	5-13, (1)
	Light rays are deflected by masses, a fact,which is correctly described in the framework of the Theory of General Relativity. If a mass is located approximately on the line of sight of a more distant source, its light rays get focused on the observer, due to the gravitational light deflection. Thus the mass acts as a lens. One refers to it as gravitaional lens. We present the main historical depelopments which lead to the recognition that light gets deflected by masses, and to the discovery on the first gravitationla lens system in 1979. We discuss also the main applications of gravitational lenses in astrophysics and cosmology, in particular for the dark matter detection.
Bachofen, R.	Biochemical cycles, microorganisms and atmospheric trace gases.	15-22. (1)
	The activity of a variety of microorganisms in soil and water contributes to a natural increase of the concentration of gases which influence the absorption of infrared radiation in the atmosphere and therefore may change the climate on our planet. Besides carbon dioxide (CO-2) methane (CH-4) and dinitrogenoxide (N-2O) are of main importance. An increase in temperature will stimulate microbial activity in most parts of the world and thus further increase the production of these greenhouse gases. Certain algae and bacterial form methylated reduced volatile sulfur compounds such as methanethiol, dimethylsulfide (DMS), and dimethyldisulfide (DMDS). These gases are oxidized in the atmosphere to sulfur dioxide acting as cloud nuclei. The microbial formation of reduced sulfur gases may therefore reduce solar input and thus partially compensate for the process of global warming. Microorganisms may also produce volatile methylated compounds of other elements such as selenium, tellurium, arsenic, lead, quicksilver, cadmium and tin. Many of these reduced organic metal compounds are unstable and therefore might be involved in atmospheric chemistry.
Lubini, Verena	Biological investigations in the Lower Reach of the Thur River (Canton of Zurich, Switzerland): I. Odonata, Ephemeroptera, Plecoptera, Trichoptera and Megaloptera.	23-31. (1)
	In the lower reach of the Thur River aquatic insects were investigated in the years 1990/91 to calculate the effects of the lowering of the riverbed on the populations and to control the recolonization. In this work only the faunistic results are presented. During the investigation 3 species of odonata, 33 species of Ephemeroptera, 21 species of Plecoptera, 43 species of Trichoptera and one species of Megaloptera were recorded. 15 of the 33 species of Ephemeroptera are rare. For two of then (Caenis rivulorum, Baetis buceratus) the Thur is till now the only known locality in Switzerland. For the first time larvae of Onychogomphus forcipatus (Odonata) are recorded in the Thur. Sialis nigripes (Megaloptera) is recorded in Switzerland for the third time. Therefore, the lower reach of the Thur is for the occurrence of several species of national, in the case of Rhithrogena germanica (Ephemeroptera) also of European importance. Abundance and biomass of insect larvae were reduced only temporarily by two ten-year-floods, which occurred in February 1990 and in May 1991.
Gasser Theo	The statistical analysis of human growth.	33-41. (1)
	Traditional statistical methods for analyzing longitudinal growth data rely on longitudinal models, which proved to be inexact in applications. In this paper new statistical approaches are presented which work without specifying a priori a model. Their application to the analysis of skeletal growth and to the analysis of parameters related to fat and weight led to new insight regarding human growth. These developments will be illustrated by selected examples.
Durrer Ruth	Big Bang Cosmology: Answers and problems.	51-59. (2)
	Since it exists, humanity has been interested in Cosmology, the question about the entire Universe. In the 20th century, cosmology has evolved into a modern science which today, due to new observing technologies, is in an especially active period. In this contribution, I describe the most important cosmological findings like isotropic Hubble expansion, primordial nucleosynthesis and the relic microwave background radiation. They have led to a reasonably complete picture of our Universe, leaving, however, a couple of open problems, some which are mentioned at the end.
Lang Walter	Pathogenetic concepts of Alzheimer dementia.	61-70. (2)
	Alzheimer disease is the most common form of dementia in old age. It is clinically characterized by a progressive disturbance of higher brain functions such as language, memory, visuo-spatial thinking, and cognition. Structural changes in the brain include neurofibrillary tangles, senile plaques, congophilic angiopathy, and neuropil threads. At present the etiology of the disease is unknown. However, numerous pathogenetic concepts have been developed, which will be discussed in this review.
Erni Guido, Preisig Hans Rudolf	Biological investigations in the lower reach of the Thur River (Canton of Zurich, Switzerland)-II. Algae.	71-78. (2)
	Algal samples were collected at nine different sampling stations in April, July and September 1990. In total, 123 algal taxa (118 species and 5 varieties) were found. Diatoms dominated with 89 taxa (84 species); chlorophytes (26 species), cyanophytes (6 species) and chrysophytes (one species) were also present. The algal diversity is comparable to that of similar rivers, which have been investigated in equal detail. Really rare species did not occur. Although some of the diatoms have not been recorded frequently in the literature so far, these are probably not rare, but have only been overlooked or misidentified in previous studies. We used diatoms as biological indicators of water quality. Our studies generally indicate moderately polluted conditions. However, at least sometimes a critical state of pollution also occurred.
Keller Peter, Hanselmann Kurt	Evaluation of the success of lake restoration treatments: Dynamics of mineralization in hypolimnetic water layers close to the sediment (Lake Pfaeffikon, Canton of Zurich).	79-92. (2)
	Lake Pfaffikon is one of the highly eutrophic lakes in the pre-alpine region of Switzerland. For the last few years, the oxygen supplied to the hypolimnion during springtime circulation was consumed regularly during the stagnation period by microbial degradation reactions. Internal restoration of lake Pfaffikon was started in 1992. During the winter months when the lake is destratified, the water is artificially circulated by injecting compressed air at the deepest location. As part of the impact assessment we followed the rates of consumption of oxygen, nitrate and nitrite as well as the production of ammonia and phosphate during the summer of 1993. Our results indicate that - dissolved compounds are distributed in the water layer closest to the sediment not only by turbulent diffusion but also through horizontal water movements, - microbial mineralization is not only active in the uppermost sediment layers but also in the hypolimnetic water layers just above the sediment, - the biogenically produced heat which is released into the hypolimnetic mineralization horizons leads to measurable changes in the temperature profile near the sediment, - by the additional enrichment of the hypolimnion with oxygen in winter the oxic conditions near the - sediment can be maintained until the end of May, - the elevated oxygen content in the hypolimnion is still insufficient for aerobical degradation of the sedimenting biomass - and to maintain oxic conditions at the sediment surface.
Straumann Norbert	Albert Einstein: On the way to the theory of gravitation.	103-112. (3)
	Einstein's early contributions to a relativistic gravitation theory are discussed in the light of his publications and his extensive correspondence, which has recently appeared in volume five of the Collected Papers. We are trying to exhibit the course of development of the theory until spring 1914.
Kaiser Klaus Felix	On the trail of the glacial climate by tree-rings and snail shells.	113-122. (3)
	The Alpine glaciation reached its maximum extent around 20,000 to 18,000 years B.P. The Limmattal Lobe of the Linth-Rhine Glacier, e.g., formed the stadials of Killwangen and Schlieren. The climatic development that had started during this coldest phase of the last ice age becomes more and more evident towards the end of the Glacial. The Late-glacial began around 12,500 years B.P., when the disintegration of the ice lobes had progressed. It forms the most interesting phase of the last Glacial and is characterized by abrupt climatic improvements interrupted by several shorter or longer reversals. The environmental conditions calm down with tile beginning of the Holocene, when the actual interglacial started. The following paper focuses on this transition between Full-glacial and early Holocene and its variations evidenced by the features of mollusc shells and annual rings of fossil trees (Abb. 1).
Knoepfel T	How nerve cells communicate.	123-130. (3)
	The neurosciences involve a wealth of data increasingly difficult to be integrated by the single scientist but also covers more general principles which have to be considered. This article on "how nerve cells communicate" is organized as a journey through the fields of neurophysiology. We start by using simplistic drawings to illustrate some general principles of interneuronal communication. How nerve cells communicate in the cerebellum, a specific brain structure, will then be described at a level of the neuronal network. The journey will finally lead to receptors for the neurotransmitter glutamate, providing examples for an outline at the structural level of molecules.
Meier Sybille, Voser Peter	Clear signs: The Lake of Zurich is recovering (Changes of the submerged vegetation as a result of improved water quality).	131-139. (3)
	In summer 1993 we studied the submerged vegetation in different places in the Lake of Zurich. The comparison of our data with recordings from around 1900 and from the early seventies showed encouraging results. The Lake of Zurich seems to be recovering. The waterplants seem to react to the improved water quality. The most important changes that we noticed are the following: The water is generally clearer than it was a few years ago. The abundant vegetation of Potamogeton pectinatus that used to predominate the submerged vegetation has disappeared in many places. Large areas of Characeae (an indicator of clean water) were found in several places. Najas marina, only rarely observed before, is now growing in the Lake of Zurich in large areas of up to one hectar. Some red-list species are spreading again. The efforts of water-protection have been successful. However, we should do everything to keep or even improve the water quality of the Lake of Zurich.
Oesch Bruno	Prions, Mad Cow Disease and Other Prion Diseases: Molecular Concepts.	149-154. (4)
	Spongiform encephalopathies are neurodegenerative diseases such as Creutzfeldt-Jakob disease in humans, scrapie in sheep or bovine spongiform encephalopathy in cattle. The infectious particle has been characterized in molecular detail leading to the identification of a host encoded protein (denominated prion protein) which in a modified form is part of the infectious particle. Different concepts for the infectious particle and the role of the prion protein in the normal and the infected animal will be discussed in this review.
Pircher Hanspeter	How does the immune system distinguish between self and foreign?	155-163. (4)
	The generation of an effective immune response involves lymphocytes which are able to react against foreign invadors. In contrast, lymphocytes do normally not respond against self structures This state of specific immunologic non-responsiveness against self is called tolerance. Why does the immune system not respond to self? The low frequency of lymphocytes, reactive to a particular antigen and the lack of appropriate reagents to detect such cells in vivo hampers the experimental analysis of immunologic tolerance. To circumvent these problems, transgenic mice were generated which expressed on most T-lymphocytes one type a particular receptor specific self antigen. These mice allowed new approaches to investigate the mechanisms of T-lymphocyte tolerance which is discussed in this review.
Amann Anton	The Gestalt Problem in Chemistry: The Generation of Molecular Shape by the Environment.	165-174. (4)
	Quantum systems have a holistic structure which implies that they cannot be divided into parts. In order to create subobjects of a system, the Einstein-Podolsky-Rosen correlations between all the subentities, e.g., all the molecules in a substance, must be suppressed in the perceptional process. It is not at all clear how this happens in detail! One can think of a psychological or a quantum-mechanical explanation. In the latter case, it would be necessary to discuss the observer (or at least a measurement apparatus) quantum-mechanically. I do not want to go as far as that. My only intention is to make plausible that very similar aspects and problems are interesting for Gestalt perception and quantum mechanics (not all of them will be discussed): Holistic aspects, creation of objects, dressing procedures, influence of the "observer", classical quantities and classical structures. It is possible, in particular, to explain the main characteristic features of quantum mechanics using phenomena of Gestalt perception (and hence without using the mathematical formalism of quantum mechanics). Optical "illusions" and single molecules will be used to illustrate that point. Incidentally, it will be argued here that at least part of a molecule's shape can be generated "automatically" by the environment. A molecular shape of this sort arises in addition to Lamb shift-type energy corrections.

1993 138th.
Kissling, E.	Seismic Tomography: Imaging the Earth's Interior with Earthquake Waves	1-20, (1)
	Seismic tomography has evolved from a combination of mathematical solutions to the inverse problem of medical tomography and classical methods of seismology into the most powerful tool available at present to image the 3-dimensional structure of the Earth's interior. Under ideal circumstances and when top quality data are used we may presently resolve complex structures of the size of a few kilometers with high confidence. Tomographic images of the Earth's mantle reveal large-scale lateral variations of seismic velocities that generally correlate well with continents and mid-ocean ridges and may be interpreted as the result of large-scale convection in the mantle as postulated by plate tectonics. Subduction zones are destructive plate boundaries where two plates converge thus forcing one of the plates to plunge into the mantle where it slowly disolves at great depth. In southern Alaska the oceanic Pacific plate is subducted beneath the continental North American plate and this process results in high seismic, volcanic, and tectonic activity. High-resolution tomographic images of subduction zones may contribute to a better understanding of the subduction processes. Local earthquake seismic tomography has been successfully applied to study in detail the 3-dimensional subsurface structure of volcanoes. As demonstrated by examples from Long Valley (California) and Yellowstone (Wyoming) the method is particularly valuable when searching for magma chambers.
Blum Hubert E	Recombinant DNA technology: Principle and medical applications.	21-36. (1)
	Recombinant DNA technology is of increasing significance for the diagnosis, therapy and prevention of human diseases. The principle of recombinant DNA technology is demonstrated and the medical applications are discussed. Apart from unanswered scientific and medical questions, legal and ethical issues have to be solved.
Woelfli Willy	Accelerator mass spectrometry and environmental research.	37-66. (1)
	Accelerator Mass Spectrometry (AMS) is a new ultra-sensitive single atom counting method, allowing to determine the concentrations of the most relevant long-lived cosmogenic radionuclides. These isotopes are deposited chronologically in the archives of our earth, such as trees, polar ice, lake and deep sea sediments. By measuring their concentration profiles, which in most cases is possible with AMS only, information on past changes in solar activity, geomagnetic field and earth climate can be obtained over long time intervals. After a brief description of the method, three examples of application will be given to demonstrate how this complex profiles can be deciphered and what consequences this information for modern environmental science have.
Wehrli Bernhard	Chemistry at the sediment surface in lakes.	69-79. (2)
	Biogeochemical cycles in lakes are strongly influence by thin biofilms at the sediment-water interface. Rapid transformation reactions at this boundary determine the fate of chemical species: Dissolved components diffuse back into the lake, solid fractions are burried with the sediments and remain isolated from the biosphere for geological time scales. High resolution in-situ sampling with dialysis samplers and direct measurements of diffusive fluxes with sediment landers yield quantitative estimates of the dominant processes at the sediment water interface. The application of such methods is illustrated with results from a study in Lake Sempach, an eutrophic Lake in central Switzerland. This lake is artificially oxygenated in order to keep oxygen concentrations in the deep waters above a limit of 4 mg O-2/l. However, this technology cannot prevent that the sediment surface turns anoxic in summer. As a consequence manganese and iron oxides dissolve and the adsorption capacity of the sediments for phosphorus remains low. A decrease in external phosphorus loading from agriculture is necessary in order to diminish the sedimentation rates of organic carbon and to restore the phosphorus binding capacity of the sediments.
Oertli J Jakob	Problems of analysing the environment.	81-104. (2)
	A useful analysis of the environment must be capable of predicting events in the system. Energy and matter are exchanged between environment and object, and an analysis of the environment should predict the type, velocity and extent of these interactions. Taking soil analyses as an example, it has been shown that the above-mentioned conditions are rarely if ever met. The reason for this is that the experimenter is usually satisfied with having obtained a particular analytical value of uncertain relevance; local soil conditions are taken into consideration only insufficiently or not at all. A remedy may be the mapping and measuring of stable soil properties which determine soil reactivity (e.g. towards potassium or phosphorus). Once this reactivity is known, it is sufficient to make simple analyses periodically so as to establish the actual state of the system in order to make accurate predictions and choose the best management. Such procedures pave the way for adequate agricultural production with minimal damage to the environment and form the basis for establishing legislation whose aim is environmental protection.
Schoop, Ralph W.	Alptransit - The Railway Tunnels through the Base of the Swiss Alps - Geologic Considerations	105-119, (3)
	Planning and construction of the two rail tunnels through the Swiss Alps will be strongly influenced by the geologic prognosis and its effectiveness in predicting zones of different rockfabric. This is especially important in the Gotthard, where the former sedimentary cover has been strongly altered during the alpine orogeny. An early treatment of these sheared shists and sucrose dolomites will be necessary to avoid delays in the progression of the Fullbore Tunneling Machines which will be used wherever possible. Because of the length of the Gotthard tunnel, 50 km, and an overburden of up to 2500 m it is planned to start construction from both ends and from one or two intermediate shafts in order to optimize time and costs. About half of the Lötschberg tunnel (total length 35 km) will be in the sediments of the Helvetic and Ultrahelvetic nappes. The flat lying folded marls and shales are difficult to predict and require numerous shallow boreholes. The drainage system in the karstified limestone of the Doldenhorn nappe is largely unknown and may cause problems during construction. Special attention has to be taken to avoid influencing the groundwater system of the deeply incised valleys of the Kander and Gaster.
Sticher Otto	Ginkgo biloba: A modern phytomedicine.	125-168. (3)
	Phytomedicines based on extracts from the leaves of Ginkgo biloba are used in the Federal Republic of Germany and in France a rather long time for the treatment of peripheral vascular insufficiency and cerebrovascular insufficiency, and disturbances of cerebral function. In Europe, commercially available preparations based on the special extract EGb 761 have a turnover of about 500 million US dollars. Meanwhile also in Switzerland various Ginkgo preparations are on the market. In this review taxonomy, botany, chemistry, pharmacology and clinical applications as well as quality control of Ginkgo biloba and phytomedicines based on leaf extracts of this plant are described. Research work of the own laboratory dealing with quality control is discussed in detail.
Oertli J J	The ascent of sap in trees.	169-190. (3)
	A large, vigorous tree can in the course of a day raise 1000 liters of water from the soil into the crown and transpire it into the atmosphere. This corresponds to several ten thousand liters per hectare and day. The tallest trees known today reach heights of 100 m. This raises the question how it is possible that such large quantities of water are transported to these heights. There is no evidence of a pressure pump mechanism and a suction pump is, according to the teachings of physics, restricted to a maximum lift of ten meters. Capillarity in conductive elements can raise water to a few meters at best. Our current view is that, nevertheless, water is raised by some kind of suction. As a consequence, the sap pressure must be negative, i.e. it is under tension. However, under these conditions water vapor is more stable and the liquid water should boil. Boiling, however, is hindered because of a high activation energy required for the formation of a critical bubble size. Nuclei that usually assist the formation of vapor bubbles are missing in the flow system of plants. They can be introduced by air entry through pores in the surrounding walls. The danger of an air seeding increases with the pore size. Bubble formation causes an emboly of the conductive element. It will be emptied of liquid water and becomes dysfunctional. It can become functional again only under specific conditions that are rare in a tall tree. Several mechanisms offer some protection against negative turgor pressures and their consequences. Reinforcements of vessel walls protect against collapse, long vessels of wide diameter reduce pressure losses during flow, and thus the incidence of an emboly whereas small, short vessels offer a better protection after an emboly has occurred, because the damage is localized. Bordered pits of gymnosperms possess some kind of valve that closes the pits after an emboly has occurred in a tracheid. This way, embolism is kept from spreading to other conductive elements. Perhaps embolism is a critical factor that limits the heights of trees.
Kucera Ladislav J	City trees.	191-202. (3)
	Trees fulfil in settlement areas along roadsides or in parks numerous tasks. At the same time, they are exposed to some extremely negative growth and living conditions. These conditions lead to an accelerated aging (expressed by low vitality) as well as to numerous diseases, caused in many cases by wood-destroying fungi. Non-vital or diseased trees constitute a high risk for their environment by creating accidents through broken or overthrown branches and stems. It is one of the most important tasks of urban tree care to recognize such potential risks and to take the necessary steps to eliminate them. In this present paper, methods and instruments for the investigation of the internal tree condition are presented. Particular attention is paid to the Vitamat, an instrument developed at the SFIT in Zurich. This instrument makes the detection of hidden fungal decay in stems and branches possible in a quick and quasi-nondestructive manner.
Sauter Willi	The entomological collections at the Institute of Entomology of the Swiss Federal Institute of Technology.	203-218. (3)
	The history of the Institute of Entomology has been presented several times on the occasion of jubilees with emphasis on teaching and research. As a complement the museological aspect will be stressed here and above all events during my time as a curator of the collections are reported. A commented list of the collections that are preserved in our collections is given.
Burckhardt, J.J.	Rudolf Wolf (1816-1893)	227-229 (4)
Larcher, Verena	The Diary of Rudolf Wolf 1835-1841	231-240 (4)
	Rudolf Wolf kept a diary for the years 1835-1841 which is mainly devoted to his study trips to Vienna, Berlin and Paris and his first two years in Berne. These notes are a valuable source not only to Wolf's biography, but also to the cultural history of the period. The following text aims to give an impression of the diary.
Balmer, H.	Rudolf Wolf at Berne	241-256 (4)
	In his time as a college teacher in the Swiss town of Berne since 1839, Wolf made his fundamental discovery of the connection between sunspots and geomagnetism. But nearly nobody heard about this. Wolf was known as a good teacher for geometry and physics, and even more as a friend of gymnastics and an excellent guide for summer wanderings with his pupils in the Alps. Since 1847, he was responsible for the little observatory of the University. In the small Bernese scientific Society, he spoke about many subjects, e.g. meteorology or earlier Swiss mathematicians. Many of these communications have been printed in the Reports which he founded in 1843 and edited till 1855, when he went back to Zurich. He was also the keeper of the archives of the Swiss Society of Natural Sciences. They are still preserved at Berne. Wolf was very active for them and created an immense collection of original letters written by naturalists between 1760 and 1870.
Lutstorf, H.	Rudolf Wolf's Years in Zurich, 1855-1893	257-266 (4)
	Rudolf Wolf lived and worked after 1855 until his decease 1893 in Zurich, holding a lectorate at the University and a professorship at the Polytechnicum for astronomy. Until 1861 he was also a teacher of mathematics at the Upper Gymnasium. Being director of the astronomical observatory he initiated the erection of the new Federal Observatory (1862-1864). As head librarian of the Polytechnicum he created the present ETH-Bibliothek with its rich treasures of first editions (15th to 19th centuries). At the same time Wolf acted as president of the Geodetical and the Meteorological Commissions.
Friedli, T.K.	Rudolf Wolf as a Pioneer of Sunspot Research	267-281 (4)
	Fascinated by the sighting of a large sunspot-group, Rudolf Wolf began his continuous sunspot observations at Berne Observatory in 1848. As an apt index to quantify the apparent sunspot activity, he introduced sunspot relative numbers by adding ten times the number of groups to the number of individual spots. This index soon became an international standard and is still in use today. In 1852 he discovered independently of A. Gautier and E. Sabine the correlation between the periodicities of sunspot- and geomagnetic-activity. To support this discovery, he made use of historical sunspot records and thus was able to verify the sunspot periodicity back to the year 1610 and to determine the average duration of the sunspot cycle to 11.11 years. After moving to Zurich in 1855 he was appointed Professor of Astronomy at the newly established Eidgenössische Technische Hochschule (ETH). Here he founded the Swiss Federal Observatory in 1864 whose first Director he became; he initiated the famous series of Zurich sunspot observations which was continued by his successors A. Wolfer, W. Brunner and M. Waldmeier, and is still continued today on Wolf's original telescope.
Ineichen, R.	«... and I will stand the hazard of the die»	283-298 (4)
	The empirical estimations of probabilities play an important role in the applications of probability theory. In order to get such empirical estimations, the astronomer Rudolf Wolf performed an impressive number of experiments involving dice, needles and cards. - The present work starts with a description of the notion of «statistical regularity». We then go to some of Wolf's dice experiments and we describe his tentative theory of the «real dice». We conclude with his results about the ancestor of Monte Carlo's method in the context of Buffon's needle problem and the random matching of two equivalent decks of cards («probleme de rencontre»).

1992 137th.
Bentor, Y. K.	Geological Events in the Bible	1-27(1)
	The books of the bible contain numerous, frequently very exact, descriptions of geological events. Some of these are discussed here: earthquakes and their accompanying landslides (the crossing of the River Jordan), seiches and tsunamis (the flood), flooding (Sodom and Gomorrah), faulting, burning gas seepages (the Burning Bush) and volcanism (Mount Sinai). These geological events appear in the biblical text mainly for artistic reasons; they serve as a suitable background to dramatize the biblical account; they create a supernatural atmosphere for the main stories, but the time and place at which they occurred are of no importance to the narrator and might be shifted freely.
Embrechts, P.	Randomness	23-40 (1)
	Randomness enters human thinking and behaviour, and physical modelling at every possible level. Starting from every day interest on lotteries, to for instance intricate problems related to nuclear reactor safety, most human endavour is to some extend governed by the laws of chance. In the present paper we give a more detailed description of one particular experiment allowing us to travel the often winding road from experiment to mathematical theory. Via a short excursion through the history of probability theory we spend some more time on stochastic modelling in insurance by discussing some of the key questions asked in risk theory. Finally, some examples relating to lottery problems should warn the reader that a superficial intuition on randomness often leads to false conclusions.
Primas H	Reorientation in natural sciences	41-62 (1)
Huber M	Fibonacci numbers	65-76 (2)
	After a brief introduction to the life and the work of the Italian mathematician Leonardo Fibonacci (about 1170-1240) his famous rabbit problem and its solution are presented. This solution consists of a recursively described sequence of numbers, today called «Fibonacci numbers». The explicit formula for the Fibonacci sequence is named after Binet; it contains the ratio t of the golden section. Another interesting connection between the golden section and the Fibonacci numbers was already described by Kepler in his «Harmonices mundi». This background may help to explain the important role that Fibonacci numbers play in the leaf and floret arrangement of plants (phyllotaxis). For instance, they appear in the capitulum of compositae; the florets of a sunflower head are arranged in two families of spirals, and the numbers of these spirals are, with rare exceptions, two consecutive Fibonacci numbers.
Busch, G.	Albert Mousson, 1805-1890, Erster Professor für Experimentelle Physik in Zürich	77-89 (2)
Holenstein E.	Philosophy, the (other) Sciences, and Life	91-105 (2)
	The special sciences, according to a common view, successively emancipated themselves from philosophy and became independent disciplines. However, medicine can also claim mothership in the genealogy of sciences. Moreover, there can be seen today a counter-movement, a kind of rephilosophization of the sciences. The reason thereof is the theory-ladenness of all experience. The openness of the problems of foundation has as its consequence that philosophy can no longer assume the role of a normative and critical judge, but only a task of evaluation. Divergent world views are compatible with one and the same science. It is possible to interpret these views as continuations of pre-scientific conceptions.
Cogoli Augusto	Biology and biotechnology in space.	109-122. (3)
	Although biological experiments are carried out in Space since two decades, it is only after the advent of the european laboratory Spacelab in 1983 that scientists are able to carry out a systematic program of investigations. The focus of this paper is on cell biology. The results available today clearly show that cells from all steps of evolution change their behavior dramatically in space. Microgravity and cosmic radiation as well may be responsible for the effects. The objectives of space biology are basic research, biomedical diagnostic and bioprocessing. With the advent of the permanent manned space station Columbus at the end of this century a significant expansion of the research in microgravity is expected.
Balderer Werner	Saltwater-Freshwater, a problem of coastal areas only?	123-142. (3)
	The availability of freshwater is an essential condition for the existence of life on the continents. As source of drinking water rain-, surface- and ground water with low mineralisation can be used according to the legal standards for drinking water. In coastal areas the fresh groundwater is underlain by the heavy mineralized sea water. The two liquids remain separated by the interface. Its location is given by the state of hydrodynamic equilibrium (M.K.Hubbert, 1940). Within the continents saline groundwaters (and brines) are present within sedimentary basins and the deep crystalline basement. In regions of semi-arid to arid climate shallow saline groundwaters can be formed under unfavorable or disturbed natural conditions of equilibrium of the different components of the water cycle. Therefore it is of vital importance not to disturb the natural conditions by agricultural land use practices and groundwater exploitation in such a way that derogation of landscape and/or freshwater containing aquifers results by the process of salting or of saltwater intrusion, respectively.
Wäffler, H.	Kernphysik an der ETH Zürich zu Zeiten Paul Scherrers (no Abstract)	143-176 (3)
Jetzer, P.	Dark Matter in the Universe	181-206 (4)
	A number of astronomical observations show that at least 90% of the gravitating matter in the Universe is dark. We discuss in some detail the evidence for this and present also arguments for the hypothesis that the average density of the Universe might well be close to the critical value. In this likely case 99% of the matter must be dark and the main content of the Universe consists of unknown nonbaryonic forms of matter. The questions of the nature, origin and distribution of dark matter belong to the most important issues of present day astronomy and fundamental physics.
König Gabriele M, Wright Anthony D, Oechslin Stephan M, Sticher Otto	Natural products from marine organisms and higher plants.	207-225. (4)
	Natural products play an important role in drug discovery. The isolation of bioactive compounds depends on the careful selection and fractionation of biological material. Consideration of these criteria led, in our laboratory, to the isolation and structure elucidation of new and/or biologically active natural products from samples belonging to a wide range of taxa. The natural products discussed provide an insight into some of the characteristic secondary metabolites to be found in marine algae, sponges and higher plants of the family Papaveraceae. Explanations concerning the structure elucidation of compounds focus mainly on the use of two-dimensional NMR-techniques. Sensitive in vitro bioassays were applied to evaluate the biological activity of the isolated natural products. Compounds with antimalarial, antiinflammatory and cytotoxic activity are discussed.
Endress Peter K	On Christian Konrad Sprengel's work two hundred years after its publication	227-233. (4)
	In 1793 Christian Konrad Sprengel's classical work «The Discovered Secret of Nature in the Structure and Fertilization of Flowers » appeared (five years earlier the book had been announced for the first time in the «Magazin für die Botanik», published in Zurich, the first botanical journal of the world). Sprengel's work initiated floral biology as a scientific discipline. Sprengel investigated almost 500 species of flowering plants and discovered the pervasive role of insects in the pollination of flowers; he showed many fundamental adaptations in the structure of flowers to these symbioses. Floral biology has developed and expanded in the last decades. But due to the worldwide threat of biodiversity it becomes increasingly apparent how many aspects of these symbioses are unknown, especially on the level of entire ecosystems and larger scale diversity.

1991 136th.
Börner, G.	The Spatial Distribution of Galaxies	1-12, (1)
	During the last few years redshift measurements of galaxies have revealed a variety of spatial structures in the distribution of the lumious matter. The difficulties to understand these distributions in the framework of a cosmological model stem from the contrast between this inhomogenous distribution and the remarably uniform cosmic microwave background. A special model, the so-called pancake model is briefly described.
Bonsen K J M	Vessel occlusions in hardwoods.	13-50 ( 1)
	Vessel occlusions in 65 species (45 genera, 24 families) have been investigated. Occurrence, types and morphology are given, relations between occlusion type and tree species, initiation (causes, circumstances), development, function, technological consequences and the prevention of vessel occlusions are discussed. The study is based on a literature survey. Swiss grown woods show two main types of vessel occlusions: tyloses and gums. Whether a plant produces gums only, or gums and tyloses depends on the gap size of the vessel-parenchyma-pits; is this larger than 3 mu-m tyloses are produced. In evolution the first angiosperms occluded their vessels with tyloses. Later the pit sizes decreased and the plants occluded their vessels by gum plugs. Because of the increasing vessel diameter plants had to return to tylosis formation secondarily. Tylose formation is initiated by oxygen, hormones (endogenous or microorganisms' hormones), or a break-down of the osmotic regulation of the parenchyma cells. Occlusion of vessels only takes place when the parencyma cells are vital enough, when there is sufficient water and starch available and when the temperature range is right. Taking part in the compartmentalization is the primary function of vessel occlusions.
Zbinden Gerhard	Toxicological assessment of drugs obtained by biotechnology.	51-65 (1)
	Through application of fundamentally new methods of biotechnology it has become possible to manufacture pure. biologically highly active proteins and polypeptides. With these substances exciting new therapeutic possibilities were created. For the experimental assessment of safety of biotechnology product. many new problems have arisen. The major ones are the species-specificity of many of these agents that normally occur only in humans, and the immunological processes set into motion when these proteins and polypeptides are administered to laboratory animals. Nevertheless. experience gathered up to date indicates that at least part of the adverse effects of biotechnologically manufactured drugs can be detected in animal experiments. However, it is necessary to abandon the conventional safety testing methods and to develop testing strategies that take into consideration all biological and chemical characteristics of each individual new drug.
Dimroth Peter	Energy conservation in anaerobic bacteria.	77-91 (2)
	The first forms of life on the earth were anaerobes, because an 02-containing atmosphere formed only after the development of photosynthesis. Extended 02-free areas exist even on earth today, which are occupied by anaerobic microorganisms. These organisms can degrade a broad spectrum of organic compounds, but use only a few mechanisms for the conservation of biological energy. These mechanisms are in part identical or similar to those of their aerobic counterparts. A huge number of anaerobic bacteria synthesize ATP entirely by substrate-level phosphorylation. Others use a chemiosmotic mechanism for ATP synthesis. The electrochemical gradient of protons required as driving force for the ATPase is created by an anaerobic respiratory chain, in which oxygen as terminal electron acceptor is replaced by a less strong oxidant, e.g. sulfate or sulfur. In Propionigenium modestum, an electrochemical Na+ion gradient is created over the membrane by decarboxylation of methylmalonyl-CoA, which is used for ATP synthesis by a particular Na+-translocating ATPase. Oxalobacter formigenes in a 1:1 exchange of oxalate for formate forms an electrochemical proton gradient which is used for ATP synthesis. The exchange is driven by the decarboxylation of oxalate, developing a concentration gradient over the membrane which for oxalate is directed from the outside to the inside and for formate from the inside to the outside.
Gassmann F.	The most important findings related to the greenhouse problem.	93-104  (2)
	The physical basis of the greenhouse effect can easily be understood qualitatively and quantitatively by a few simple relations. The scientific conclusions of the World Climate Conference 1990, which are identical with the IPCC report, can be reproduced and critically analysed. We must be aware that the long range climate forecasts probably have to be corrected towards higher temperatures. Even without this possible intensification of the problem, we have to judge future climate change on the paleoclimatological background as dramatic in respect to its amplitude and also to its rate of change. Atmospheric concentrations of carbon dioxide and methane together with temperature variations during the last ice age suggest an instable global climate system amplifying small perturbations. In spite of many scientific uncertainties, it is clear today, that planet earth is going to execute a major transient having important implications on its development for a very long time. If this anthropogenic process will be in favour of mankind and the whole biosphere is uttermost questionable.
Merz B	The fruit-flies of the town of Zurich (Switzerland) (Diptera: Tephritidae).	105-111 ( 2)
	31 fruit-fly species (Diptera: Tephritidae) were found in the town of Zurich between 1987 and 1990. Crepis taraxacifolia is a new host plant for Tephritis matricariae (LOEW). The phenology, host plant relationships and the association of the flies to different habitats are discussed.
Schwyzer M	Which came first, the virus or the host?	113-130 ( 2)
	Neither the viruses nor their pathogenesis have left a fossil record. No existing virus isolates are more than 80 years old. Yet, epidemiology and molecular analysis of contemporary viruses infecting animals and man contribute to an increasingly clear view of their distant predecessors. Viruses and viroids also inspire speculation about their possible involvement in the origin of life, because they are among the simplest entities carrying instruction for their own multiplication. However, since the rate of virus evolution is roughly a million times higher than that of the host, this question may never lead to a conclusive answer.
Sticher H	Conservation of our natural resources: The soil case.	137-149 ( 3)
	Soil protection includes all direct and indirect measures which support the conservation of the different soil functions in a balance proportion. In order to preserve the soil as the basis of life and as an adequate habitat of mankind, animals and plants, it is essential to keep a sufficient area for primary production, to secure fertility and productivity of the soil at long sight, to maintain adequate nature protection reserves and to limit land consumption. Following general considerations about the endangering of soil quality by human activities, the soil protection policy of Switzerland is presented, present regulations are critically reviewed and somm supplementary measures are suggested.
Apel K	The light-dependent control of chloroplast development in higher plants.	151-161 ( 3)
	In the absence of light higher plants form etiolated seedlings whose plastids are devoid of chlorophyll. In these socalled etioplasts the biosynthesis of chlorophyll leads only to the formation of the immediate precursor of chlorophyll, to protochlorphyllide. The subsequent reduction of protochlorphyllide to chlorophyllide requires light. Upon illumination of etiolated higher plants chlorophyll accumulation starts and at the same time the photosynthetically active membrane system of chloroplasts develops. The light-induced transformation of etioplasts to chloroplasts is controlled by at least two different genetic systems. To a lesser part plastid proteins are encoded by the plastid DNA and the resulting mRNAs are translated at plastid-specific ribosomes. The majority of plastid proteins are encoded by nuclear genes and are synthesized in the cytosol as higher molecular weight precursor polypeptides that are transported into and processed within the plastid compartment. The interaction of the two genetic systems is under the control light. The effect of light is mediated by at least two distinct photoreceptors. Phytochrome as one of these photoreceptors controls the transcription of nuclear genes that encode light-dependent plastid proteins. The second photoreceptor, the protochlorphyllide reductase, catalyzes the light-dependent reduction of protochlorophyllide to chlorophyllide within the plastid and affects also the light-dependent chloroplast development. The interaction of these photoreceptors has been studied in mutants in which the function of either one of the two photoreceptors has been abolished by mutations.
Turner H	Inventory and threat situation of the molluscs in the canton Zurich, Switzerland.	163-181 ( 3)
	Almost 100 years after the first catalogue of the Zurich molluscs, which comprised approximately 100 valid species, its revised edition is presented. During the last two centuries c.160. Recent species of molluscs (106 land snail, 33 freshwater snail and 21 bivalve species) were recorded in the canton Zurich, i.e. 60% of the number of Recent molluscs species in all-Switzerland. It is likely that 13 additional species (mainly slugs) may be detected through intense search. Six species are supposed to have disappeared from the canton Zurich since a prolonged period, and ten additional species could only be detected as fossils in deposits of the Quarternary, Gyraulus laevis and Unio crassus are rated to be in danger of extinction (threat-category 1), whereas eight species must be classified as strongly threatened (threat-category 2). No less than 47 additional species appear to be threatened due to decline and destructiuon of their habitats or to their rarity (threat-categories 3 and d4). Altogether, 40% of the mollusc species in the canton Zurich either have disappeared for appear to be endangered. Separately treated are eight adventitious species of which only a few became established. Five species immigrated (or were imported) during very recent times and are expanding. In conclusions, on the basis of the Swiss mollusc data bank some habitats are designated which are in need of protection because of occurrence of threatened or rare species.
Blum H	Greenhouse effect and plant growth.	189-206 (4)
	Calculations of present day climate with models indicate great errors. These models are not validated. They proved to be very sensitive on variations of different cloud parameters which have not been determined yet with sufficient accuracy. Some sensitive processes are not yet included. The model predictions are not reliable. The increase of global temperature for the last 100 years has been evaluated with questionable assumptions and coffections. The value of approx. 0.5 0C is within natural variation of climate. The amount and the geographical pattern of this increase don't agree with the predictions. The antarctic tee-cores contradict the greenhouse-relevant cause-effect relation. The CO2 increase promotes plant growth mainly by two effects: A CO2 doubling increases photosynthesis significantly, such that a growth increase of approx. 25-100% is effected. The optimum temperature of growth increases about 2 0C, thus plants would even profit from a moderate temperature increase. A decrease of transpiration which can cause a growth increase, too. Water use efficiency is approx. doubled, i.e. with limiting water supply, plant growth would nearly double. These effects all continue to increase beyond a CO2 doubling. The demand for a reduction of CO2 production is reasonable for the most industrialized countries but it would be catastrophic for the developing countries.
Egloff F G	Permanence and change in the flora of Laegern.	207-270 ( 4)
	The geological and topographical diversity of the region of Laegern (Switzerland, cantons Aargau and Zuerich) shows a flora rich of vascular plant species which is typical for the lowland of Switzerland and for the northeastern Jura Mountains on the one side, specific for this region on the other side. The landscape has undergone an intensive change since the turn of the century, which shows an influence on the flora. The past flora of a number of areas and localities and of the whole region is partially reconstructed by the study of old herbaria, excursion notes and of floristical publications, and comparisons with the present state are made. Factors of threats and possibilities for preserving the floristical diversity and the local historic species are debated.

1990 135th.
Niederer P	High technology in medicine.	1-16 (1)
	Present diagnostic methods are aimed on the one hand at allowing for a preferably noninvasive application and, on the other hand, at being specific for a certain disease. An unspecific and useless application should a priori be avoided. Many procedures which are available or still being further developed today and which fulfil these requirements to a high degree, are in essential need of high technology. In many cases a procedure could not even be envisaged without the use of high technology. Computed tomography, ultrasound methods and new procedures of computerassisted evaluation of x-ray images serve as examples to document the importance of high technology. Furthermore, in therapy improved treatment methods become available due to the use of advanced technology. A well-known example for such a development is lithotripsy with the aid of mechanical shock waves.
Burga C A	Vegetation history and paleoclimatology.	17-30 (1)
	The introduction gives a short overview to the palaeobotanical and palynological research in Europe. The main important palaeoclimatological methods are the following: Pollen analysis, dendrochronology, oxygen isotopes analysis, CO2 analysis, glacier oscillations, löss stratigraphy, weathering, erosion and accumulation of soils, sea/lake level fluctuations, planktonic foraminifera, fossil beetles assemblages, etc. The main problems of palaeoecological reconstructions with pollen analytical methods are discussed. The following points are important: Natural succession, soil forming phases, plant immigration, immigration pathways and possibilities, concurrence, vertical vegetation zonation. Late Würmian and holocene Swiss alpine climate oscillations and timber-line fluctuations since the Alleröd-Interstadial are discussed. In the western Central Alps the timber-line increased during 1000 years at the beginning of Holocene at about 500-600 m. During the post-glacial climate optimum (Atlantic) the timber-line reached its highest extension at about 2300 m above sea level, and the snow-line reached up to 3100 m. The most important climatic deterioration during the Boreal (8500-7200 years B. P.) is characterized in the Central Alps by a marked recession of Pinus cembra (Oberhalbstein-/Schams-/Venediger-Oscillation). This recession has been recorded in several pollen diagrams in the Grisons, the Valais, the Bernese Alps, the Salzkammergut, the Hohen Tauern, and the Southern Tyrol. Boreal dry periods may explain the Pinus cembra recession as a result of frost dryness. At the end the paper gives an outline of the development of the Swiss central alpine forest belt and the snow-line since the late Würmian.
Nievergelt B	Ecological strategies as a model to understanding problems of animals and man in a particular environment.	31-46 (1)
	With the well-known r-K-strategies we have a simple ecological model, that is helpful in efforts to understand complex systems such as a particular species of animals or plants in their specific environment. As examples the Kingfisher, the Roe deer and the Alpine ibex are treated. In addition - although in a more speculative manner - human society is considered for which a partial and therefore especially critical change in strategy is described. In applying a simple ecological model to reality, which is always more complex, we can never expect a complete correspondence. However, it is shown that the value of a model becomes particularly evident in the analysis of those characters that do not coincide between reality and model.
Stettler, P	Martin Wagenschein's Nature-Philosophical Approach	47-61 (1)
	In the introduction we briefly describe the pedagogical work of Martin Wagenschein, in whose centre stands original understanding and precise thinking. The process of understanding physics can only succeed if it is not regarded without certain presumptions, but as limiting itself on the measurable. It is this self-limitation of their subject that many physicists seem do disregard, if they want to interpret a meaning of the universe from its unified theory. Wagenschein's philosophical interest centres on the creation of physics from the living world. This epistemological path is described in the example of a cord's sound. On the question about the nature of light it is pointed out in a Wagenscheinian manner that light as such is not visible. By this means even the beginner will realize the parabolic character of light-waves and photons and their complementary relationship. Wagenschein sees the true pedagogical value in the understandability of nature, in the discovery of an enigmatic order in the universe.
Hitzig, W. H.	Long-term Observations of Diseases in Childhood	73-88 (2)
	In my fare-well lecture on retiring from the Kinderspital Zurich, I discussed with the students longterm observations in patients with blood diseases. As a common denominator I pointed out the decisive influence of medical knowledge and skills on quality of life or on survival of these children. - The patients presented the following problems: 1. A hereditary hemoglobin anomaly (Hb Zurich): the bearers of this gene are essentially asymptomatic, but suffer severe hemolytic attacks after ingestion of sulfonamides and other drugs. - This is a typical example of an iatrogenic disease. 2. A cancer of the kidney (nephroblastoma, Wilms-tumor) which may help to understand the pathogenesis of malignant degeneration. This child was cured by combined therapy, but toxic side-effects of a drug damaged the myocardium and later necessitated a heart transplantation. 3. A case of leukemia in a 4-year-old girl was successfully treated 23 years ago. She could later lead a normal life, got married and gave birth to two normal children. 4. A boy with familial congenital severe combined immunodeficiency syndrome (SCID) was successfully treated by bone-marrow transplantation two years ago and is now normally developped.
Klingler J, Kunz P, Buser A	The vector nematode Xiphinema diversicaudatum and the arabis mosaic virus of strawberries on the Swiss plateau (Switzerland).	89-96 (2)
	The ditribution of X. diversicaudatum in Switzerland is shown in a map (figure). Compared with earlier maps new finds have been added, but the known geographical distribution pattern remains unchanged: East of the Walensee and Zurichsee basins and of the Limmat valley, Switzerland remains void of any finds of this species. According to Sturhan, the same is true for the adjacent south German area. X. diversicaudatum has been found west of the just mentioned geographical axis exclusively. The hypothesis therefore is maintained that this species is not occurring in soils originating from deposits of the eastern Alps which are rich in chalk, whereas it occurs in soils derived from deposits of the central and western Alps, which are rich in silicates. The occurrence of the arabis mosiac virus (AMV), which is vectored by X. diversicaudatum, is strongly related to the abundance of the vector. The virus has always been found if populations exceeded 400 nematodes per liter of soil; it has never been detected in places where vector densities were below 100. In between, the virus has sometimes been found and sometimes not been found (table). These relations enable prognoses to be made regarding the risk run by strawberry plantation to the damaged by the arabis mosiac virus. The occurrence of X. diversicaudatum is related to soil parameters. It was confirmed to clearly acid to neutral soils. Among the soil types, most findings were made in sandy loam and - less frequently - in loam.
Eiberle K	The importance of forests for the animal kingdom	117-127 (2)
Hasler F	Perspectives on the pathogenesis of rheumatoid arthritis.	129-138 (3)
	Rheumatoid arthritis (RA) is a complex disease of unknown etiology in which genetic, hormonal, and immunologic factors interact to produce joint and systemic manifestations. Both the humoral and cellular arms of the immune response appear to participate. Locally produced antibodies complex with an inciting antigen, yet to be identified, within the joint and activate the complement system, resulting in articular inflammation mediated primarily by polymorphonuclear leukocytes and their products. Chronic inflammatory cells then produce soluble factors that induce both tissue destruction and inflammation. RA is an example of a disease in which the central immune recognition event involves CD4 lineage helper T cells interacting with polymorphic class II HLA molecules.
Mancktelow, Neil	Displacement, Deformation and Fabric of Rocks	139-154 (3)
	Deformation structures can be observed on all scales within orogenic zones such as the Alps, where two continental land masses have collided. They represent the final form acquired due to relative movements of the rocks over millions of years, and their geometry is relatively well known from detailed field studies. The current challenge is to attempt a reconstruction of the movement history, i.e. the kinematics, from the available field data. To this end, various forms of scale models are particularly useful, as they allow study of the progressive development of deformation structures. The models may be smaller-scale field examples of major structures, rock mechanics experiments in which time, stress and temperature are scaled but the rock material is the same, models using analogue materials (e.g. paraffin wax), or mathematical models. The results of modelling can then be applied to field studies: as an example, in interpreting movements on major fault zones such as the low-angle extensional normal fault which is well-exposed between the Simplonpass (Valais) and Domodossola (Italy).
Schonle E J	The child with diabetes mellitus: Between immunology and psychology.	155-168 (3)
	Childhood diabetes (Type-1-diabetes) is based on the lack of the essential hormone insulin. It is now widely accepted, that the development of Type-1-diabetes is the consequence of an autoimmune destruction of the insulin-producing beta cells of the pancreas. However, a genetic predisposition is required. In addition recent results from molecular genetic research suggest a susceptibility gene in the HLA-region on chromosome 6. Trigger substances inducing the initial beta cell destruction are not known today. Finally all insulin producing cells are destroyed, life long insulin replacement therapy cannot be circumvented. Optimal treatment delays or prevents diabetic late complications. Precondition for optimal therapy is an extensive education of the child an the parents, an exact diet with known amounts of carbohydrates, multiple insulin injections and home blood glucose monitoring. Prevention of the autoimmune destruction is not yet possible up to now.
Merkle H P	Delivery systems for transdermal therapy: Approaches, chances and limits.	169-190 (3)
	There are not many fields in drug formulation where the complexity of modern pharmaceutical research can be so clearly demonstrated as by the sequence of ups and downs taking place in the field of transdermal delivery system development. The basics to this area include the anatomy and biochemistry of the skin, the polymer chemistry of relevant polymers, the manufacturing of laminated polymer patches and the pharmacokinetics and pharmacodynamics of controlled delivery of drugs. Equally important are questions about the effect of so-called absorption enhancers on the integrity of the skin, the mechanisms of transport control in laminate systems and how to affect the thermodynamic activity of drugs in relevent carriers. The essential question, however, is concerned with the safety and the risks of such therapy. This work is aimed to illustrate the need for a multi-disciplinary approach to make progress become possible in spite of rather narrow boundary conditions.
Siegmann H C	Combustion aerosols.	197-219 (4)
	Progress in many areas has led to an improved knowledge of the deleterious effects of the primary (smoke) and the secondary (smog) combustion aerosols on human health, weather, and plants. Physical characterization and measurement of the combustion aerosols provides the basis for urgent improvement of the air quality. The notoriously difficult soot is built from homogeneous spherules, the primary tar particles, on which poisonous chemicals are adsorbed depending on the type and mode of operation of the combustion device. Soot particles are agglomerates of hundreds of primary tar particles, yet their optical absorption is adequately described by the concept of fractal structure despite the bizarre shapes, and their size range in the transition between the applicability of Mie- and Rayleigh-theory. The adsorbates of the soot particles may be classified according to their desorption temperature by photoelectric charging. Additionally, the photoelectric aerosol sensor offers a simple way to dynamically determine the total mass of the carcinogenic polycyclic aromatic hydrocarbons (PAH) adsorbed on the particles. Legislature should thus be able to generate new rules for the survey of combustion devices that are better adapted to the present needs and state of knowledge.
Grauer R	The disposal of highly radioactive wastes: Chemical aspects.	221-238 (4)
	The safety of the storage of highly radioactive wastes relies on a system of sequential technical and natural barriers. Wastes from reprocessing of fuel elements are immobilised in glass and the glass is embedded in steel canisters of 25 cm wall thickness. The disposal tunnels are backfilled with swelling bentonite clay. The backfill has approximately one meter thickness and represents an efficient transport barrier because of its low hydraulic conductivity and goood sorption properties. Very long-lived radionuclides, only, survive transport in the backfill. Some of these have low solubilities in groundwater. For most of them migration through host rocks and overlaying sediments is retarded by adsorption. For all of them matrix diffusion contributes to retardation. Safety assessments have to prove that dose exposition resulting from disposal does not exceed the regulatory limit. For a reliable safety analysis knolwedge of long-term performance of technical barriers and chemical behaviour of radionuclides along a potential migration path is necessary. In this, a phenomenological description is insufficient; required is the understanding of relevant reaction mechanisms.
Vonarburg C, Ruoss E, Burga C A	Bioindication with epiphytic lichens on horse-chestnut trees around Lake Zurich (Switzerland).	239-258 (4)
	At sites close to the shore along Lake Zurich the lichen vegetation has been studied on 131 horsechestnut tree-trunks (Aesculus spec.). A lichen index calculated from the total cover and the number of species showed in the investigation area a clear gradient to a better developed lichen vegetation towards southeastern direction. Even at sites with a high lichen index, species sensitive to air pollution are rare and show little cover. Furthermore, a clear tendency to a better developed lichen vegetation has been made evident from sites close to the center towards sites which are situated outside urban areas. Similar trends are shown by the zonation into six lichen zones including further parameters like damage and vitality of lichens. According to the results of zonation and lichen index, there is a decreasing concentration of lichen damaging pollutants from the northwestern towards the southeastern part of the investigation area. Compared to the results of the lichen studies the immission data of technical measurements indicate a dominant role of sulphure dioxide as lichen damaging pollutant whereas a synergistic effect together with other substances is very probable.
Schiess H	Reed stands as habitat islands of birds.	259-265 (4)
	The influence of various ecological parameters on the occurrence, species diversity, and species frequency of breeding birds was investigated in reed stands of the Lake of Zurich and Obersee, Switzerland. The homogeneous and sharply delimited reed stands constitute habitat islands in the surrounding landscape. A total of 212 reed stands were mapped photographically and their form, size, and structure were determined. Three types of reed stands could be distinguished, each with characteristic features and typical avifauna. A survey of breeding birds in these stands revealed 1816 pairs of the following 13 species, listed in order of decreasing frequency: Grebes, Coots, Reed Warblers, Reed Buntings, Marsh Warblers, Great Reed Warblers, Moerhens, Mute Swans, Little Grebes, Water Rails, Savi's Warblers, Gray Herons, and Little Bitterns. The relationships of site parameters are discussed, and detailed observations are presented on Little Grebes, Little Bitterns, Reed Buntings, Marsh Warblers, Reed Warblers, and Great Reed Warblers. Statistical analysis showed area of the reed stand to be the single most important site parameter.

1989 134th.
Schneebeli M, Kuettel M, Faeh J	Three-dimensional development of a peat bog on a slope in Toggenburg, Switzerland.	1-32 (1)
	In connection with the restauration of a peat bog on slope the development of the peat was investigated with palynological methods. The bog is situated in the Upper Toggenburg (Switzerland) and is partially exploited or drained. A boring core for the reference pollen profile was taken at one of the deepest sites of peat. Every 5 to 10 cm a pollen sample was counted. Additionally 10 samples are radiocarbon dated. To determine growth and spread of the peat on a grid with 50 m side length at 43 sites, samples were taken at the interface between peat and underlying mineral soil and on two transsect in three depths. The history of vegetation of the mire of the past 10,000 years, as well as of the region, could be interpreted by means of the reference profile. Calculation of the pollen accumulation rate enhanced the interpretation in the early phases of development. The visual stratification of the percentage pollen diagram was used to relate the basis and transsect samples to the biostratigraphical zones. In a second approach the basis and transsect samples are dated through numerical correlation between reference profile and sample. The resulting date was more precise than the visually related sample where the pollen percentages are appropriately transformed. An estimation of error by application of different correlation methods showed that 90% of the samples could be dated within +- 880 y. The dated samples are visualized with maps. The bogs has spread from two centres at the edge upward. During this spread it climbed over several steps. Although the horizontal spread ceased about at 0 A.C. because of geological reasons, no decrease of the vertical growth is visible until the 19th century.
Niederer, U.	Comets, Moons, New Stars: the role of Observation in the Copernican Revolution	33-54 (1)
	While observations played a minor role for Copernicus himself they later influenced considerably the improvement and the reception of the Copernican system. Several types of influence may be distinguished. The observations made by Tycho Brahe were the primary motive for Kepler to modify and develop the system. The newly appeared stars of 1572 and 1604 and the comet of 1577 showed that changes in the heavens were possible, hence the Aristotelian views on the nature of celestial bodies, which formed the basis of traditional astronomy, could no longer be correct. The moons of Jupiter, discovered by Galileo in 1610, demonstrated that there were other centers of motion besides the earth, which in turn made the heliocentric system more credible. Newer and better observations made it ever more obvious that in applicability, too, the new astronomy was superior to the older one.
Scharfetter C	Medicine and anthropology.	56-66 (1)
	Science (and therefore medicine too) is a culturally determined system of cognitive structuring. A holistic approach to medicine should take into consideration somatic-physiological, psychological, social as well as transpersonal perspectives towards illness and healing. The ubiquitous suffering creates a multitude of healing offers. Western academic medicine has developed as a profession with claim for monopoly as the only valid healing system, based on empirical positivism of natural science. Common factors appear to be operative in various healing procedures.
Landolt E	Environmental tolerance test: Introduction and conclusions.	67 (1)
Schmid W A	Basic principles of methodological procedure in environmental tolerance tests.	68-73 (1)
Margulies H P; Trachsler H	First experiences with administering environmental tolerance testing.	74-80 (1)
Duetsch H U	The Antarctic ozone hole: An anthropogenic feature.	85-108 (2)
	The very complex modern photochemical theorie of atmospheric ozone is described in which odd oxygen destruction is predominantly produced by catalytic cycles with reactive radicals. It is demonstrated that the observed ozone distribution can only be understood on the basis of a tight coupling between similarly complicated chemical and transport processes. The ozone hole which developed in the Antarctic spring since the late seventies is produced by anthropogenic chlorine which is activated in the extremely cold air at the end of the polar night in the lower stratosphere predominantly by heterogeneous reactions. This process happens in an air mass which covers most of the Antarctic continent .and which is due to the prevailing dynamic conditions practically isolated from the surroundings. The active chlorine destroys after the return of the sun the ozone by catalytic cycles which are more complicated than these of the normal photochemistry. There is a tight relationship (feed back mechanisms) between chemistry and circulation.
Bolliger T, Eberhard M	New fossils from the upper freshwater molasse of the Hoernli region (Eastern part of Switzerland).	109-138 (2)
	The Molasse sediments of the Hoernli fan have been divided by different authors into lithologically different sequences and thus widely correlated. This artificial division is not satisfactory and of minor value due to the fast changing sedimentary conditions within fluvial deposits. Fossils were only occasionally found. E. Letsch 1899 first described the occurrence of a thin coaly marl with fossil leaves on Chlihoernli at 930 m. In 1986 M. Weidmann (Jongny VD) successfully prepared some other dark marls for Microfossils. More recently our systematic search for fossils in that region lead to the discovery of several additional horizons in the profile. A provisional biostratigraphy of the uppermost fossil-containing layers indicates the presence of MN 6-7. (MN means Micromammal-Unit of Neogene age). Phytozonation indicates that OSM 3a-3b are present. The plant associations of Leiachertobel and Chlihoernli are that of modern mixed mesophytic forests. Climatically, both Chlihoernli horizons can be described as warm temperate, with a mean annual temperature of 15-17 degree C and a mean annual precipitation of over 1300 mm. At Leiachertobel the provisional results indicate a slightly cooler climate. Paleotopography at Chlihoernli (930 m) was rather flat and at or lower than 350 m above sea level, whereas at Chlihoernli (1000 m) the increase of mesophytic and mountainous species indicates an accentuated paleorelief.
Specker, E.	Logic or the Art of Programming	139-150 (2)
	The fundamental ideas of logic programming are explained by considering a puzzle (the Towers of Hanoi). The possible positions of the puzzle form a graph, two positions being joined by an edge if they can be transformed into one another by a legal move. Two realizations of this graph are introduced: one in our material world with the help of a copying machine, the other in the ideal world of Herbrand with the help of logic programming.
Potrykus I	Gene technology in plants.	165-174 (3)
	Methods have been developed during the recent years which open up the possibility to transfer isolated genes into somatic plant cells and to regenerate subsequently complete plants from these genetically altered cells. Such "transgenic" plants differ normally from the original plants only with regard to the novel character caused by the gene added. The "foreign" gene can originate either from a plant or from other organisms. As soon as it is integrated into the genome of the acceptor cell it behaves exactly like other original genes of the host plant. The foreign gene can also be changed prior to its transfer, e.g. by an alteration in the regulatory signals which decide where and when in the plant the gene will be activated. Gene technology thus offers possibilities for precise and predictable alterations of plants. This is understood by part of the population as great opportunity, by others as a big danger. Both views probably exaggerate. It is rather difficult to construct dangers on the basis of transgenic plants, and the possibilities for plant improvement via gene technology are rather limited.
Kucera L J	Potential applications of NMR tomography in wood research.	175-196 (3)
	The nuclear magnetic resonance tomography is a non-destructive method, which renders two dimensional figures of water distribution in wood. The potential applications of this method in forest and wood research are summarized. In the introductory chapter, the role of the water in tree physiology, wood science and wood technology is outlined. A critical review of the established methods of the determination of the water content in wood is presented. The fundamentals of the nuclear magnetic resonance tomography are briefly outlined. The advantages of this new method are visualized by numerous examples. In conclusion, a list of the potential uses of the nuclear magnetic resonance tomography in the research fields of tree physiology, wood science and wood technology is presented.
Mittelstrass, J.	Copernican or Keplerian Revolution? - Kepler's Cosmology, Philosophy and Methodology	197-215 (3)
	In the history of science and ideas the name Copernicus stands for a fundamental change in theoretical and methodological matters. Here, the fact is overlooked that the Copernican programme is in reality a conservative one and that the revolution in question takes place no earlier than within the framework of the Keplerian astronomy. Copernicus tries to revalidate an old research programme in astronomy, whereas Kepler breaks with this programme and starts with a new development which, from the point of view of physics too, leads far beyond classical astronomy. In order to illustrate a «Keplerian revolution» attention is paid to Kepler's kinematical and dynamical explanations. Further passages deal with the Keplerian achievements, the harmonies of the cosmos and the Keplerian unity of philosophy and science of nature.
Wolters G	Fourteen philosophy of science theses on the problem of new kinds of forest damage.	216-223 (3)
Lubini-Ferlin V	Ecological survey of streams within the city of Zurich (Switzerland).	229-250 (4)
	The habitat structure of 84 streams with a total length of 70 km was surveyed from 1986 to 1988 within the city limits of Zurich. The faunal composition of ten selected streams was studied in more detail. Twelve species of mayflies, fourteen species of stoneflies and 48 species of caddisflies were found. For the first time in the canton of Zurich, I recorded the occurrence of species of mayfly, Baetis scambus and Ecdyonurus helveticus, and found larvae of the dragonfly Cordulegaster bidentatus at two new localities. Overall, 109 taxa were recorded during the study. In general, more species were found in large and highly structured streams with a regular water flow than in small streams with a periodic water flow. Waterweeds in high abundance were found in Sagentobelbach, Dorfbach Affoltern and Katzenbach. The evaluation revealed that eighteen out of 84 streams were in a satisfactory ecological condition. A comparison of my fauna list with data from the end of the last century suggests that the fauna composition of stoneflies and caddisflies in Wehrenbach and Stockentobel has changed over this period.
Straumann, N.	Neutrinophysics and Supernova Explosions	251-280 (4)
	At the end of the thermonuclear evolution of a massive star the burned out central region becomes unstable and collapses in almost free fall. Thereby a neutron star or a black hole is formed. The exterior parts of the progenitor star may, under certain circumstances, be expelled by a powerful shock wave. This cosmic firework appears then as a supernova. By far the largest part of the energy released in the collapse is, however, radiated away in a gigantic neutrino pulse. This neutrino radiation was the first time detected in underground laboratories a few hours before the supernova SN 1987A flared up in the Large Magellanic Cloud. This enabled us to test quantitatively our theoretical ideas on gravitational collapse and neutron star formation. Detailed observations of the further evolution of SN 1987A are of invaluable importance for the study of stellar evolution, nucleosynthesis, and the physical processes at the birth of a neutron star. The supernova 1987A in the Large Magellanic Cloud will be a major focus for astrophysical research for many years to come.

1988 133th.
Bolliger T, Gatti H, Hantke R	Geology and paleontology of the Zurich Oberland (Switzerland).	1-24 (1)
	New scientific research within the Zurich Oberland may add some new aspects to the knowledge of Molasse and Ice Age. Several nodular limestones are explained as calcicrusts, built up under semi-arid conditions. Coarse, chaotic conglomerate sequences may be interpreted as sediments of cooler climates. The finer grained homogeneous conglomerates are still thought to be of fluvial genesis. The fossil remains of plants and mammals found in marls indicate warmer climates than today. The mollusks of the Upper Freshwater Molasse prove that there were only a few places within the region with stagnant waters, such as lakes and ponds. The Upper Marine Molasse is a 100 m thick sequence of sediments, built up during a short period of a marine influx. It shows sedimentary structures due to rapid changed depositary conditions. Dense forests protected the landscape from erosion during warmer periods; valleys must have been deepended in colder times. Toss and tributaries eroded along thrusts, faults and regions of weak and soft lithologies. The Upper Lake Zurich basin is the remainder of a broken up anticlinical system. The main events from the Molasse times to late Ice Age shaped the landscape of the Zurich Oberland.
Zürcher E	Methods for the diagnosis of tree health and vitality.	25-42 (1)
	The morphological, physiological, chemical, and physical aspects of ageing in wood, and of changes in the xylem cell vitality, are presented. The influence of microorganisms upon these processes is outlined. Methods of ascertaining tree health and vitality as related to the current forest decline are described. In conclusion, extended applications of the established procedures and equipments as well as promising new methods in this field are reviewed.
Stoll K	Developments during four decades of arboriculture in Switzerland.	43-50 (1)
	In Switzerland the traditional forms of arboriculture with standard fruit trees has been replaced by intensively managed areas with dwarfing rootstocks. The rising need for table fruits with long storage abilities has given impulses for growing new varieties. But oecologistic circles and lovers of old varieties are angry about this radical change. The traditional standard tree may still maintain his place for delivering fruits in home use and in the industry of fruit products.
Schweizerische Arbeitsgruppe für Reflexionsseismik	First Results of the Traverses Across the Alps of NFP-20	61-98 (2)
	NFP-20 is a research program of the Swiss National Science Foundation, with the goal to study the crustal structure of the alps. Three reflexion seismic traverses across the alps are supported by 20 additional projects in the field of geoscience. The eastern and western traverses were recorded in 1986 and 1987, the southern traverse is planned for fall 1988. The data processing is done internally in the Swiss institutes, the ETH in Zurich and the EPF in Lausanne. First results of the eastern and western traverses show the regular southward plunge of the european crust underneath the alps. The highly reflective lower crust and the Moho band can be traced to a depth of 16-17 sec. (48-51 km) below the pennine nappes. There they end abruptly, to reappear again in the southern portion qf the eastern traverse at a depth of 15 sec. (45 km). The refraction Moho however is continuous across. The external massives appear as upthrusted portions of variscan upper crust with a detachement surface near the top of the lower crust. The pennine front can be traced as a strong band of reflectors, plunging southward from the Rhone valley to a depth of 5-6 sec. near the Swiss-Italian border. The sedimentary layers between the Gneis nappes show up as good reflectors. The two traverses shot so far, cover only the northern protion of the alps. The structural features on the southern slope of the alps, such as the so called root zone and the lvrea body will be studied this fall in the southern traverse.
Schluechter C	New geological observation at the mammoth site at Niederweningen (canton of Zurich) (Switzerland).	99-108 (2)
	Geological and geotechnical investigation in the area of the famous Mammuthus primigenius site at Niederweningen give evidence for a more precise litho- and climatestratigraphic positioning of the fossiliferous Quaternary beds: these sediments including an underlying Eemian peat are highly deformed by thermokarst diapirism and by later compaction faulting. The geocryologically active event is correlated tentatively in climatestratigraphic terms with the maximum ice extent of the Last Glaciation. The Niederweningen fauna is older than this event as evidenced by palynostratigraphic data as well.
Sauter W, Huber P	Pharyngomyia picta (Meigen) (Diptera, Oestridae) as the agent of human ophthalmomyiasis.	109-113 (2)
	A case of human ophthalmomyiasis externa caused by Pharyngomyia picta from the Puschlav valley (Grison) is reported. So far this species was not known as a human parasite, his genuine host is the red deer (Cervus elaphus). There are only few dates on the distribution of Ph. picta in Switzerland, all are located in the canton of Grison.
Wolters, G.	Evolutionary Epistemology - a Polemic	125-142 (3)
	Evolutionary epistemology can be viewed as an evolutionary, i.e. not as a "philosophical" but as a scientific" investigation of our epistemological capability and its achievements. The presumed, at least partial correspondence between the structure of our knowledge and the structure of the world is the ma in problem. I argue in this paper that the evolutionary approach to knowledge is circular and "metaphysical". This approach, moreover, is inadequate from a conceptual point of view and represents an obsolete variant of Darwinism that is capable of "explaining" almost everything in evolutionary terms ("Panglossism"). The anthropological and ethical claims made under the name of "Copernican revolution" are a new edition of what is in principle an unsuitable and unacceptable attempt at a scientific grounding ("naturalism") of human self-understanding.
Diebold, P.	The Young Palaeozoic Trough of Northern Switzerland and its Prospects for Bituminous Coal	143-174 (3)
	The paper reviews on the basis of data published by Nagra aspects of sedimentation, tectonics and coal prospects of the Young Palaeozoic Trough of Northern Switzerland. The sedimentary fill of the Trough consists mainly of terrestrial fluviatile and lacustrine deposits and has been subdivided in two parts: The older part, of Stephanian to Autunian age, seems to be restricted to the central part of the Trough and comprises e.g. the coal measures and the Lacustrine-Series, the latter characterised by bituminous shales. The Lower Alluvial Fan-Series is indicative of synsedimentary tectonics and placed at the upper boundary of the sequence. The younger part is reaching unconformably far beyond the central part of the Trough and comprises the Playa- and the Upper Alluvial Fan-Series. The structure of the Young Palaeozoic Trough is dominated by probably synsedimentary, transpressive tectonic features characterised by strong lateral variations in relief, folds and over-thrusts. After this transpressive phase culminating at the boundary between Lower- and Upper Permian, only weak extensional faulting is suspected for the period of the Upper Permian. The coal measures discovered in the well Weiach contain approx. 60 seams and stringers varying in thickness from 0.1 to 4 m with a total of approx. 32 m of coal. The coals are limnic, allochthonous and have a high ash content. They range from subbituminous- to medium volatile bituminous. The main seam of 4 m is at a depth of approx. 1585 m and has the following quality: Ash content (Raw coal): 10-18%; Volatile Matter: 31-33%; Calorific value: 28-31 MJ/kg; Sulphur: 0.48% (WAF); Coking property: positive; Vitrinite reflectivity: 1.01 (R max). Today no mature technology is available to work the seam. However, speculative coal prospects exist at a viable depth between 900-1200 m in the overthrust blocks located west of Weiach.
Hächler, P.	Analysis of the Weather Situations Leading to Severe and Extraordinary Avalanche Situations	175-186 (3)
	Based on the records of the Swiss Federal Institute of Snow and Avalanche Research (SFISAR) some of the most severe and disastrous avalanche situations for about 100 years were selected. Northerly and southerly exposed regions are described separately. It was found in nearly all cases that a quasi stationary trough has led to such situations. Frontal developments, led by strong winds towards the Alps have intensified much the quantities of snowfall, specially at the windward slopes. The barrage gradients seem to be important, but there were no extremely high values found. For the recent cases upper air information is also considered. Usually there was a well defined jet found, indicating active frontal mechanisms. Finally the possibilities of modern methods are discussed. It is shown that numerical modeling gives quite reliable indications for several days.
Hürlimann J, Schanz F	Characterization of two connected ponds with a small catchment area on the basis of plankton biocenoses and nutrient loadings.	205-224 (4)
	An investigation of chemical, physical and biological parameters in two connected ponds (catchment area = 0.7 km-2) in Kusnacht, Canton Zurich, was carried out from February to October 1987. The most important results, described in sections 3.1-3.5, are summarized here: 1) both Rumensee and Schubelweiher have a mean depth of 1.1 m. The mean inflow is 370 m-3/d into Rumensee and 320 m-3/d into Schubelweiher (mean water residence times: 38 and 52 days respectively). 2) Oxygen conditions were found to be good even when the ponds were iced over. Oxygen concentrations below 4 mg O-2/l were observed only once during the summer. 3) Both Rumensee with 66 taxa and Schubelweiher with 95 taxa were found to possess extremely species-rich plankton biocenoses. Blooms of Chrysophyceae species suggest nutrient-poor conditions. 4) For each pond, the phosphorus freight due to the inflows was around 5 kg P/yr and that due to direct precipitation on to the pond surface was around 1 kg P/yr (total phosphorus loading: 408 mg P/m-2 cntdot yr in Rumensee; 374 mg P/m-2 cntdot yr in Schubelweiher). According to the nutrient loading models of R. A. Vollenweider (1976), the phosphorus loading in both ponds exceeds the critical level of tolerance-this conflicts however with the biological assessment. 5) The fact that the two ponds are connected results in the existence of rather better physical, chemical and biological conditions in the lower-lying Schubelweiher than in Rumensee, which, as the higher of the two, takes on the function of a nutrient retention basin.
Bosshardt Hs. Paul	Developments in agricultural pest control.	225-240 (4)
	Intensification of agricultural production has reached limits: further increases would result in production of surpluses and in environmental contaminations and other damages to soil and water. This situation requires a more pronounced orientation of agricultural production towards integrated production, i.e. towards high quality goods and improved, ecologically sound methods. Plant protection against pests, diseases and weeds is an important sector. Integrated plant protection tries to solve this difficult problem by combining a variety of methods adapted to the annually changing situation: agronomic methods (crop plant varieties selected according to local conditions, crop rotation), administrative measures (plant quarantine), use of biological (beneficial arthropods, fungi, bacteria and virus) and biochemical agents (pheromones), application of carefully selected chemicals (specifically active, degradable compounds in appropriate formulations and well aimed applications) and the use of technical means (traps, weed combs) are combined to an effective, environmentally sound and socially acceptable system. By this flexible system, which requires precise observations of nature, the farmer can safeguard natural productivity and harvest good and sufficient crops.
Arnold Benz	Radio Astronomy of the Sun and the Stars	241-256 (4)
	In the last few years more and more stars have been found to emit radio waves. Most of these discoveries are made with the Very Large Array, the most powerful radio telescope of the world. The experience of the past 40 years of solar radio astronomy is tapped to interpret the stellar sources. Radio emission mainly carries information on the outer atmosphere of stars, in particular on the density, the temperature, the magnetic field and its related very energetic processes, which widely determine the state of atmospheres. These processes also occur - with mostly unknown consequences - during the formation of stars out of the interstellar gas. Young stars are extraordinarily active and emitters of radio waves.

1987 132th.
Gensler G A	The climate of Zurich (Switzerland).	1-18 (1)
	Weather systems produce the variety of instantaneous states of the atmosphere. Climate introduces the longer time scales and may be regarded as average weather or long-term state of the atmosphere, including mean values as well as frequencies and extremes. The urban climate of Zurich and its environment is influenced by local terrain features, modifying the regional macroclimate within the temperate westerly wind belt in mid-latitudes. Zurich climate data, mainly based on the site of the Swiss Meteorological Institute (SMI), show, a temperate, humid climate with prevailing unsettled weather, especially in spring and early summer. Relatively pleasant is autumn with its longer spells of fine weather. Autumn and winter present a gradual increase in temperature during this century; spring and summer are again at a normal stage after the remarkable warm and dry period between 1942 and 1953. Due to local topography the natural ventilation is reduced, causig increased problems in air pollution.
Straub M	Muskrats in the canton of Zurich (Switzerland).	19-25 (1)
	Musk-rats escaped from animal-farms for furs begin to behave like indigenous species in several parts of Europe, so in the canton of Zurich. By digging their holes they damage engineering works along rivers. For this reason they are controlled and their further expansion is being prevented by different measures.
Burga C A	Geomorphological and pollen analytical investigations on late- and post-Wuermian deposits in the Grisons (Swiss Alps).	26-44 (1)
	This study presents some results of investigations about late- and post-wurm maximum glacier extensions in the Grisons (Swiss Alps). The last Wurm-maximum glacier extension terminated before the Oldest Dryas (before 13,000 BP), and the Bolling-interstadial was characterized by the spreading of Pinus, Betula, Juniperus, and Hippophae. Until the end of Bolling the Wurm glacier transfluences over the alpine passes of Lukmainer, Bernhardin, Julier, Maloja, Bernina, La Stretta, and Viola have been terminated. After the Bolling-interstadial, the alpine glaciers grew again to the Egesen-stage. During the Allerod-interstadial, Pinus spread up to 1600 meters above sea level. The climatic depression of the Younger Dryas lead to a clear diminuation of Pinus and to an increase in herbaceous plant vegetation cover. Investigations in the Wurm ice-marginal zones of Feldkirch, Sargans, Chur, and Valtellina allow to model the glacier melting process since the Wurm-maximum. During the Gschnitz-stage, several glaciers (Hinterrhein, Landwasser, Inn, Poschiavino, and Adda) existed independent from each other and, in the Central Alps, the tree line climbed over 2100 meters above sea level since the early Holocene. The Post-Glacial can be characterized by the following climatic fluctuations: Palu (Praeboreal), Oberhalbstein (Boreal), Misox (Older Atlanticum), Piora I/II (Younger Atlanticum), and Goschenen I/II (Subatlanticum).
Brunner, W.	Stone with cup-marks near Wetzwil (municipality of Herrliberg, ct. of Zurich)	45-52 (1)
	From the stones with cup-marks, which are today near the Swiss Federal museum, was that of Wetzwil, Herrliberg, the most remarkable. Astronomical and geographical analysis shows, that all directions of sunrises and sunsets at the beginning of the seasons can be found by tangents on the brims of the cup-marks for the astronomical and the natural horizon (a0... f36 and g-4). Extreme differences of directions from 42° to 46.5° to east-west by moonrise and moonset over the 1° elevated natural horizon are marked with cups (h45, i45... m42. . .and q46.5). In the year 2700 B.C. the North Polar Star was a Draconis (Thuban) and the meridian t90 could be oriented with it. Later on in the year 1700 B.C. Thuban oscillated 9° to the north direction. The extreme deviations were noted by cup-marks fixing r81 and s81. The stone shows also directions to other stones with cup-marks and cult centres. It is uncertain if and when all those possibilities were practised.
Nievergelt B, Anzenberger G, Stucki B, Zingg R	Altitudinal zonation of mammals, birds, and some selected plants on the western slopes of Mount Kenya (Kenya).	53-64 (1)
	In a reconnaissance study along the routes to and from Point Lenana characteristic species of plants and all observed mammals and birds were recorded systematically in steps of 50 meters. This study was done to enable comparisons with other afroalpine regions. It was conducted within an ethological and ecological field ocurse of the Zoological Institute at Zurich University, section Ethology and Wildlife Research, in northern Kenya. Table 1 shows the altitudinal zonation of the vegetation and the range of the registered plants including their flowering phase. The Hagenia-Hypericum-zone was most clearly separated from the adjoining zones. In a second table the recorded mammals and birds are listed with their altitudinal ranges. We would like to mention for the montane belt Black and White Colobus, Bushbuck, Hartlaub's Turaco, for the alpine belt Rock Hyrax in rocky places, Augur Buzzard, Jackson's Francolin. Slender-billed Chestnut-wing Starling, Scarlet-tufted Malachite Sunbird and Tacazze Sunbird were found only in places with flowering lobelias. Most common and striking animals were the Hunter's Cisticola sbd a duetting bird species sbd and the Hill Chat. In comparison with corresponding zones in the more extended alpine ranges of the Simen mountains of Ethiopia, the species diversity seems to be definitely lower and in the abundances of some characteristic plant species the wetter climate became apparent.
Heinloth, K.	Are fossil fuels an alternative to nuclear energy?	69-87 (2)
	As large sources of energy actually only fossil fuels and nuclear energy are disponible, renewable energy sources cover - at least in the FR of Germany - just a small amount of energy demand. In further future solar and fusion power plants are perhaps disponible as large energy sources. Utilization of fossil fuels and nuclear energy are connected with high damage risks: Continued utilization of fossil fuels in actual rates causes an increase of global temperatures by 2 to 4 centigrades by release of carbon dioxide and another 2 to 4 centigrades by emission of trace gases within the next 100 years. A thus involved climatic catastrophe would destroy the living space of hundreds of millions of men. Harm risk of actual utilization of nuclear energy concerns mainly big nuclear accidents such as Tchernobyl. Those accidents may be avoided by construction of inherent safe reactors. The menace of a C02-climatic catastrophe urges a drastic decrease in utilization of fossil fuel. This in future only may be attained, if all possibilities of saving energy, of all renewable energy sources and nucelar energy by inherent safe nuclear power plants are pursued.
Thierstein, H. R.	Paleoceanography: Global change in the history of the earth	88-103 (2)
	The central question of oceanographic research is the circulation of the oceans. Paleoceanography, in turn, is concerned with the history of the oceans and past circulation changes. As a relatively new, multidisciplinary field it has grown very rapidly, mostly due to recent developments in oceanography, marine geology, and micropaleontology. Oceanographic research results have demonstrated the great influence that oceanic circulation exerts on global environmental changes in climate, primary productivity, and chemistry of the atmosphere. Intensive geological exploration of the ocean floors in the last two decades has revealed that distribution and shape of the world's oceans have been continuously changing over geological time scales. Recent developments in micropaleontology hold the promise of improving our understanding of the causes and timing of these global paleoenvironmental changes.
Schär, M.	Actual situation in the problem of alcoholism	104-112 (2)
	1. Consumption of alcoholic beverages increased in Switzerland from 10 liters of pure alcohol per year and person aged over 15 years to 14 liters in the years 1945 to 1965. 2. Since then the total amount of consumption is stagnant, but we observe a significnat shifting in distribution of age of consumers. 3. Were are the main points in fighting against alcoholism to be put?
Kyburz, W.	Aged, but not out of date. Geology of Zurich by Alexander Wettstein	113-117 (2)
	One of the most outstanding geological theses concerning the geology of the aera of Zurich was published 100 years ago. Its main lines are still remarkable and it is well worth being remembered again
Britt H	Lichens as bioindicators of air pollution, illustrated in an IAP-map of Winterthur (Switzerland).	123-134 (3)
	The following study presents a contribution to the problem of the air pollution. To get a view of the air condition it is necessary to measure and map the degree of the air pollution. The use of bioindicators is particularly apt in this case, because bioindicators can show the manner the pollutants affect the organisms. The study especially describes the use of lichens as bioindicators and a method to map the air pollution following the principles of the "Index of Atmospheric Purity" (IAP).
Schluechter C, Maisch M, Suter J, Fitze P, Keller W A, Burga C A, Wynistorf E	The profile of foliated peat at Gossau (canton of Zurich) (Switzerland), and its stratigraphic position within the last glaciation.	135-174 (3)
	The reference section at the Gossau gravel pit has been re-investigated by a multidisciplinary approach and the bearing of its stratigraphy as well as of the geochronology on the evolution of the landscape is evaluated. The compressed peat beds represent the time span from 54,000 to 28,000 y BP and consist of several overbank depositional cycles of different magnitude without glacigenic influence. Only after 28,000 y BP a glacial advance occurred, passing the Gossau area. This advance is not just an important oscillation only, but represents an independent advance from the Alpine Border to the Foreland. The palynostratigraphy of the beds between the delta-complex (bottom) and the most recent flavioglacial/glacigenic accumulative cycle (top) reveals several oscillations of stadial/interstadial type of vegetation. Below the Upper Peat Bed a subaerial pedogenesis is detected.
Kyburz W.	The weather of Zurich 1986	175-181 (3)
	The main climatological dates of meteorological and rain-gauge-stations in the aera of Zurich are compiled and commented.
Caratsch C G	The importance of peripherally acting neurotoxins for the investigation of neurophysiological processes.	191-258 (4)
	This essay is divided into two parts. The first part contains a survey of the peripherally acting neurotoxins (NT) and a characterization of their effects. According to their specific activity the NT are classified in three groups: (1) presynaptically acting NT, (II) postsynaptically acting NT - two groups which take effect mainly on neuromuscular junctions - and (III) NT with an effect on ionic channels, especially on the sodium channel of excitable membranes. The second part is a report on studies of my own in order to analyze the mechanism of action of beta-Bungarotoxin (beta-Bu Tx), a presynaptically acting snake neurotoxin. The complex action of beta-Bu Tx was studied in detail with immunological and particularly electrophysiological techniques.

1986 131th.
Schaub, M. C.	Mobility and life	1-32 (1)
	Mobility and motility represent a basic requirement for life. Cellular sequestration by membranes against the environment is a prerequisite for life involving metabolism and self-reproduction. It is dependent on movement of the entire organism as well as for intracellular transport. The function of movement of flagella and cilia at the cell surface as well as intracellular amoeboid movement by the contractile proteins myosin and actin, its regulation by calcium ions and the necessary energy production are discussed in connection with the evolution from prokaryotes up to fungi, plants and animals. Formation and specialization of muscle tissues only occurs in the animal kingdom.
Schacher, J., Wyler, D.	Intermediale vector bosons W and Z: their significance for particle physics	33-51 (1)
	The intermediate vector bosons W and Z were found experimentally in 1983 at the European Centre for Particle Physics, CERN. In this essay we first describe the theoretical developments leading to the predictions of these particles and their importance for the understanding of the fundamental forces. Then we sketch the experimental aspects and show why they could be observed only recently.
Ribi Georg, Arter H	Colonization of Lake Zurich (Switzerland) by the prosobranch snail, Potamopyrgus jenkinsi, between 1980 and 1984.	52-57 (1)
	The fresh water prosobranch snail Potamopyrgus jenkinsi colonized most of the Lake Zurich (total length 40 km) within a period of a few years after it became established in the lake. In 1982 local population densities surpassed 100,000 individuals per square meter. In 1983 the density dropped by at least two orders of magnitude and was still low in 1984.
Wyler R, Engels M, Metzler A E	Bovine infectious rhinotracheitis virus.	73-91 (2)
	Bovine Herpesvirus 1 (BHV-1) is the causative virus of infectious bovine rhinotracheitis (IBR) and of infectious pustular vulvovaginitis (IPV). In the present paper it is shown that by means of restriction patterns and mapping of restriction sites of the DNA, BHV-1 strains can be grouped into three types. Type 3 was isolated from tissues of calves with nonpurulent meningo-encephalitis. Cross-hybridization revealed a close antigenic relationship between the three types. It may therefore be assumed that the three types are differentiated from each other only by short regions of the genomes. Additionally the immunogenic components of BHV-1 are dealt with. By means of radioactive labelling of viral proteins during replication in cells with subsequent separation of proteins using electrophoresis in polyacrylamide slab gels and by means of monoclonal antibodies it could be demonstrated that two complexes of glycosylated viral proteins jointly were responsible for a humoral immune response by inducing neutralizing and cytotoxic antibodies.
Glaser, D.	Gustatory Research in Primates	92-110 (2)
	The function of the gustatory sense organ and the importance upon the quality of life are mentioned. The efficiency of this organ is discussed within the order of primates. When comparing both, behavioural and electrophysiological methods, it appears that those compounds that elicited unequivocal behavioural reactions (either preference or rejection) produced identical results with both methods. Special effects in phenylthiocarbamide (PTC), some sweeteners, proteins and 'taste modifiers' were studied. Furthermore videotaped behaviour reaction patterns were analyzed. Finally, in accordance with the findings that are presented here, the sphere - a possible model for the relationship of gustatory qualities - is presented.
Waldmeier, M.	The Corona at the Total Eclipse of the Sun on July 31, 1981	111-118 (2)
	The eclipse was observed under ideal conditions near Bratsk (Siberia). By a camera of 50 cm focal length 16 pictures were obtained during the totality which lasted for 84 seconds. They were used for the study of the light distribution and the structure of the corona. It was a repetition of a programme that was carried out at earlier eclipses with a view to study the coronas variation during the activity cycle of the sun. The eclipse took place 1½ years after the sunspot maximum. Accordingly the streamers were straight and radial (Fig. 4) as it is the case in a maximum corona. On the other side the isophotes show a strong flattening (Fig. 7), typical for a minimum corona. Incidentally the temperature of the air was recorded during the eclipse. The minimum of the temperature was reached 14 minutes after totality and was 70 lower than the temperature to be expected without the eclipse (Fig. 1).
Schmid P	More finds: More knowledge? The history of recoveries and interpretation of human evolution.	145-160 (3)
	One of the major developments in the past 100 years has been the recovery of a substantial number of hominid fossils all over the world. A general view of the main events in the history of the finds is given. The discussion of gracile australopithecines demonstrates that the improved knowledge of human evolution required the acquisition of different classes of information. Hypothesis of narrative and mechanism can be formulated based only on findings in comparative biology. The fossils, the "hard evidence", serve to test these hypothesis. The fossil record only build up the "quantity" of possible tests. The growing amount of knowledge in comparative primatology in connection with historical information causes the change of "quality" in phylogenetical interpretations.
Buchmueller K S	Characteristics of annual rings and vessel lengths of Fagus sylvatica.	161-182 (3)
	Characteristics of annual rings and vessel lengths determine the hydraulic architecture of wood, which is of importance for physiology, pathology and technology. The characteristic of annual rings deals with the dimension, shape and frequency of vessels, and also with the proportion and the arrangement of vessel tissue in the transverse section of growth rings. Vessels are conducting units of the xylem of a finite number of individual vessel elements arranged end to end; measurement of vessel length supply new information on the indigenous deciduous trees. Observation of annual ring features shows that broad rings exhibit fewer but wider vessels than narrow ones. The actual proportion of vessel tissue varies little with ring width, although it tends to be somewhat greater in narrow rings. The maximum vessel length was nearly 88 cm. Vessels with broad lumina tended to be longer than those with narrow lumina.
Wildi O	New methods in vegetation mapping.	183-189 (3)
	Vegetation mapping is aimed to reveal states and processes in space and time. It relies on plant-ecological bases, which are a matter of scientific search. With regard to our rapidly changing environment, the topic becomes rather acute. Results have to be immediatley available, as detailed as possible and relevant for wide areas. In order to solve this problem of optimization, three approaches are presented: Specialized maps, simulation of maps based on external information related to space, and statistical sampling. While environmental changes in the past have sometimes been recognized too late, an efficient control of the vegetation is becoming operational using the new tools.
Meier, C.A.	Die Wildnis und die Suche nach der Seele des heutigen Menschen	191-203 (4)
Huber, G.	Wissenschaft und Ethos	229-233 (4)
Zürcher E R	Stem ontogeny of wych elm (Ulmus glabra Huds.) under normal and long day conditions.	235-294 (4)
	Subject of this thesis is the development and structure of the secondary stem xylem of wych elm (Ulmus glabra Huds.) in relation to formation and structure of the terminal shoot. Observations were carried out on plants one and three years old, growing under long day (greenhouse) and normal (nursery bed)conditions. Both longitudinal and radial growth exhibit periodicity which is the more apparent the longer primary growth is in progress. In the case of longitudinal growth, the length of internodes are a direct parameter of the varying degrees of shoot elongation. The first phase of longitudinal growth is the formation of that part of the shoot that has been preformed in the winter bud. During the subsequent phase additional growth occurs which may show a depression during summer. Plants growing under greenhouse conditions show longer internodes and thinner stems than those growing under normal conditions. The "basipetal gradient of xylem formation" is thus more pronounced in the former. Unlike in adult elms, in juvenile ones the innermost ring of early wood pores is differentiated simultaneously with the resumption of apical growth, and it is connected with the preformed part of the new shoot. Within one growth ring the conducting elements show variation with reference to dimension and arrangement. Early wood pores are significantly wider in greenhouse plants than in normal plants. After completion of longitudinal growth, late wood vessels are formed in a typical banded (ulmiform) arrangement. In plants growing under normal conditions this formation occurs already after the growth depression in summer.
Krause W	An attempt to determine subfossil oospores of Charophyta from Swiss lake deposits.	295-313 (4)
	This paper deals with the possibility to determine oospores of Charophytes from prealpine lake sediments, which was thought to be impossible up to now. The remainders are well preserved and therefore can be compared with specimens of recent species. Difficulties arise from the vagueness of specific characters and from the broad intraspecific variability within the large genus Chara. The main problem for the investigator is to bring aberrant oospores (Fig. 3) in relation to typical ones (Fig. 2). The genera Nitella, Tolypella, Nitellopsis, and Lychnothamnus are rather uniform in shape of their oospores. In spite of the difficulties, determination is largely possible by comparison of the unknown oospores with reliably defined recent ones. To master the enormous number of oospores in subfossil material, the binocular microscope is the most suitable instrument. Figs. 6 and 7 show oospores from neolithic lake dwellings, Fig. 7/4 demonstrates a plant which was not yet found in the prealpine region.

1985 130th.
Rasche,G.	Das physikalische Werk Peter Debye's. no abstract; german only	1-17 (1)
Busch,G.	Peter Debye (1884 -1966). Werden und Wirken eines grossen Naturforschers. no abstract; german only	19-33 (1)
Kucera,Ladislav.J.	The morphology of the intercellular spaces in the wood rays: 1. Present stand of our knowledge on the intercellular spaces.	35-74 (1)
	A literature review is presented summarizing our knowledge on the nomenclature and typology, ontogeny, systematic and histologic distribution, shap and size, constitution, functions and importance of the intercellular spaces in plant tissues.
Fritzsche Robert	The influence of optimal and defective nutrition of crops on quality of the products.	75-91 (1)
	The available supply of necessary minerals from the soil for crops, and their relation to one another, has decisive effects on the quality of the products. Optimal supply of N is critical. The oft-cited statement that farmers increase their yields with high N doses without affecting the quality is simply not true, since the maximum yield for crops is quickly reached with increasing N dosage but declines significantly above a defined optimum. Clear reductions in quality occur, together with increasing predisposition to fungal infection. Despite well developed soil analysis systems, it is still difficult to define the soil's available supply of individual minerals; this is especially true of N with the many indistinguishable and changing processes in the soil. The results of soil analysis must be accompanied by observations on the crops, especially regarding early developing disorder symptoms, and continuously improved by further research work. Above all, ionic exchange competition must be taken into consideration. Many nutritional disorders, especially in perennial plants, are not caused primarily by unharmonic absorption of nutrient, but by metabolic disorders. In such cases, allowance must be made for equilibration between the vegetative and the generative phases of plant growth, that means between the different organs and metabolic processes in the formation of the plant, for example the treetop, to eliminate disorders arising from opposing processes. For this, the specific influence on metabolic processes by the different growth promoters, such as auxin, GA and growth inhibitors such as ethylene, must be considered. In recent years, agriculture benefited from the basic research work of the Federal Institutes of Technology and the Research Stations on nutritional requirements of cultivated plants, with clear effects on the improvement of quality and texture of the products.
Hantke René	Relief development and climatic history of the central and eastern Swiss Alps: 1. Middle Oligocene to early Miocene.	92-114 (1)
	The history of valley formation and climatic variation result from combined studies of tectonics, gravel and heavy mineral contents, stratigraphy and paleoecology of Molasse fans and fission track datings of igneous rocks. Orogenic uplifts caused changes in Alpine drainage pattern, but main valley excavations were produced by early glacier advances during cool phases. Relict reliefs still exist on the former continental divide. The early-middle Oligocene Altdorf fan had 2 sources: the western Middle Grisons and the valleys of the Brenno della Greina river. In late Oligocene, after the Gotthard massif uplift, these valleys had become tributaries of the Ticino river. The Molasse fans were formed by release of lakes dammed by landslides or mudflows. The Rigi-Rossberg fans had their sources in the Schams, Rheinwald and Avers valleys. The succeeding Hohronen fan was built during the latest-Oligocene climatic deterioration. Uplift also increased glacial activity, which widened the valley-heads from the Sursess back to the Bergell and Bernina mountains, so that ice flowed through the Septimer and Julier passes to Tiefencastel. Its meltwaters initiated the Schin gorge and formed a connection with the Posterior Rhine. The Speer fan, corresponding to the lower Rigi deposits, originated in the Sursess and Arosa area, and the early Miocene Pfingstboden-Kronberg fan added the Prattigau valley to its source area. The Gaebris fan was built up by an early Ill river: the younger Sommersberg and Pfander fans were derived from the Flysch mountains of the Faneren and Vorarlberg by the Lutz, Frutzbach and Bregenzer Ach rivers.
Burckhardt,Johann Jakob	Paul Nigglis Verdienste um die Herausgabe des Buches "Die Bewegungsgruppen der Kristallographie". Note; no abstract, German only	115-117. (1)
Gansser,Augusto.	The cup-stones of the Kinabalu a contribution to the world-wide distribution of cup-stones	121-143. (2)
	Prehistoric cup like depressions, cut into the surface of rocks, are cultural objects which occur world-wide in the same way, form ans layout. Well known from the alpine areas, here mostly in connection with other petroglyphs of various significances, they have also been observed in very remote regions, such as little known examples from Himalaya, the Easter-Island, Australia and in particular from the summit region of the Kinabalu in northern Borneo, illustrate. The cup-stones of the Kinabalu, actually one of the best occurrences, seem to be related to the death cult of this peculiar mountain.
Hantke,R.	Relief development and climatic history of the Central and Eastern Swiss Alps. Part 2: Middle Miocene to early Pleistocene	144-156. (2).
	Subsidence, infilling and climatically controlled sea-level fluctuations caused again a flooding of the Swiss Plain by a shallow sea in the middle Miocene. The initial uplift of the Aar massif interrupted drainage through the Panix - Bisistal channel and reversed the flow direction: Anterior and Posterior Rhines flowed to Chur and Sargans, capturing the Plessur and Landquart rivers. The united Grisons Rhine built up the Hoernli fan to a much larger size than its Oligocene individual predecessors. At the emplacement of Helvetic and Austroalpine nappes, the drainage of the Grisons Rhine river followed the fault zone of the Alpine Rhine valley towards the newly formed Lake Constance and to the Danube. Later, the Rhine was diverted towards the Burgund Gate. In the early Pleistocene, it changed its direction into the Upper Rhine Plain.
Kucera L J	The morphology of the intercellular spaces in the wood rays: 2. Studies with the scanning electron microscope.	157-198 (2)
	Wood rays of Fagus sylvatica L., Quercus robur L. and Q. petraea Ehrh were examined by scanning electron microscopy (SEM), quantitative tissue analysis and the optical shuttle method. Special attention is given to splitting as a method of preparation for SEM studies. Triangular and rectangular intercellular spaces were observed and grouped into 4 categories according to their course. Pitting, perforations, sculpturing and contents of the intercellular spaces are described. The occurrence in the Fagaceae of ray sections with and without intercellular spaces is a useful criterion for ray classification.
Wysling,Hans	Gedenkblatt für Chlyjogg (1716-1785). No abstract	213-227, (3)
Hünermann,K.A.	Pleistocene Mammals of the Canton Zurich.	229-250, (3)
	A synopsis of the pleistocene mammals from the Canton Zurich is given in chronological sequence with detailed comments.
Kucera,L.J.	The morphology of the intercellular spaces in the wood rays: Part 3: Histological Analysis	251-310 (3)
	Shape, size and distribution of intercellular spaces are statistically analysed. Beech is shown to differ from the two oak species; however, the results for the two oak species are identical. The parameters of the intercellular spaces are strongly correlated with those of the adjacent ray cells. In the Fagaceae broad rays consist of outer areas with intercellular spaces and inner areas where intercellular spaces do not occur. Certain relationships between the intercellular spaces and their position within the growth ring or the trunk radius arise from the process of ray ontogeny.
Zürcher,E., Kucera,L. & Bosshard,H.H.	Bildung und Morphologie der Thyllen: Eine Literaturübersicht. No abstract	311-333 (3)
Cogoli,A.	Weltraumbiologie: Das Verhalten der Zellen in Mikrogravität. No abstract	334-336 (3)
Hitzig,W.H.	Prof.Gian Töndury zum Gedächtnis.	343 (3)
Ziegler,E.	Biochemical influences of the excess in refined carbohydrates on the development and function of the brain - hypothesis or fact? abstract and title	345-373 (4)
	In "western food" the excess in sugar and the other refined carbohydrates influences the neuronal and hormonal regulation of the complex biochemical and biological processes and probably disturbs through disregulations the structural development, and in children and juveniles, also the function of the brain. Similar to behaviour teratogens the sugar-excess of the mother probably induces some early behaviour problems in the child. The excess in sugar of the grown-up child seems to be the main cause of growth acceleration and of the procession of physical maturity. Sugar addiction of the accelerated juveniles of today enhances the puberal problems and causes frequently through the postprandial centraJ glucopenia the subjective symptoms of the pseudohypoglycemia, which may also enhance the juvenile delinquency.
Kucera,L.J.	On the Morphology of the Intercellular Spaces in the Wood Rays.  Part 4: Investigations Using Optical Shuttle Microscopy and General Review	374-397 (4)
	In both beech and oak, radial intercellular spaces constitute a complex network of cavities, which in spite of structural differences between the species are of equal importance for gas exchange. The intercellular spaces in the rays of oak are shorter but more intensively interconnected than those of beech. The radical development of the ray areas with intercellular spaces in the xylem part of the ray is connected with the sclerification processes in the phloem part of the ray, in terms of both development and function.
Guyer,E.V.	Ein Querschnitt durch die Geschichte der NGZ in losen Folgen.	398-406 (4)

1984 129th.
Straumann,N.	Particle physics and the early universe	1-20 (1)
	Recent developments in particle physics have important cosmological implications. The violation of baryon number in grand unified gauge theories has led, for the first time, to a rational qualitative explanation of the matter-antimatter asymmetry of the Universe. Other basic cosmological questions appear in a new light. Of particular importance are the expected phase transitions, which are associated to the hierarchy of spontaneous symmetry breakdowns of the gauge symmetry and of other symmetries in the course of the evolution of the very early Universe. The new theories have also led to speculations about the existence of exotic matter (massive neutrinos, magnetic monopoles, photinos, gravitinos, etc.), which might be important for the dynamics of the Universe and for the origin and composition of Galaxies.
Fröhlich,E.	Radiation-induced Cancer: The methods and the problems of quantitative risk assessment	21-37 (1)
	The quantitative assessment of radiation-induced cancer risk is a two-step procedure. First, the increase in cancer incidence in an exposed population has to be determined and its relation to the measured or estimated radiation dose has to be explored. Secondly, different mathematical models are used to derive probabilities for the dose-dependent extra-risk. Risk factors for small and very small exposure levels are of great consequence owing to the widespread public concern focused on this issue. This paper reports a summary of the methods which are a pre-requisite to understand the results of the BEIR III report.
Burkart,W.	Genetic risks from ionizing radiation: yesterday, today, tomorrow	39-50 (1)
	The published results in the BEIR III-report of the National Academy of Sciences (1980) concerning the genetic risks to populations exposed to low levels of ionizing radiation are summarized and commented. The various problems which appear in extrapolating animal data to humans as well as the uncertainties found in determining the radiation risk after accidental whole-body exposure lead the subcommittee to the decision to express the risk values in variation-ranges. The comparison with the UNSCEAR-reports 1977/1982 suggests that the weight of these estimations lies in the lower part of this spectrum. The genetic risk is newly defined as the number of induced effects per generation and rem. A direct estimation of first-generation expression of damage is described as well as the conventional method based on the relative mutation risk. The most important results are summarized in table 1.
Hutter,K.	Mathematical prediction of barotropic and baroclinic processes in the Lake of Zurich and the Lake of Lugano	51-92 (1)
	Some of the current and thermistor-chain data that was collected in Lake of Zurich and Lake of Lugano is physically interpreted by means of hydrodynamic models. The shallow water equations are used to determine the periods and structures of the surface seiches. The equations are integrated using finite difference and finite element methods and the Kantorovich technique. The results obtained with these methods are compared and the advantages of the various methods are discussed. Then, wind-induced currents of a homogeneous lake are treated and it is explained why satisfactory prediction of the barotropic motion in Lake of Zurich requires a three-dimensional circulation model. It turns out that the non-linear advective terms must be included in the analysis, if the local transport should qualitatively correctly be predicted. A simple criterion permits estimation when two-dimensional models are sufficient and when a three-dimensional model is necessary. Internal seiches are interpreted by means of two-layer models. Such models exist in various approximations. These are discussed, and their range of validity is delimited by determining the periods and structures of the eigenmodes. Finally, baroclinic, wind-induced currents in Lake of Zurich are discussed. The corresponding FD-model is delimited with respect to its applicability, and it is shown that it predicts quite accurately these lake processes which are directly subject to the wind; the oscillations which set in after the cessation of the wind are, however, too much attenuated.
Bosshard,W.	Die schweizerischen Waldbesitzer vor der Bedrohung sterbender Wälder.	93-98 (1)
	(note)
Michel C; Meier M	Radiation effects on prenatal development.	105-123 (1984)
	Prenatal development is characterized by its high radiosensitivity. Therefore, radiation exposure of an embryo or a fetus is of great concern for human health. Irradiation during gestation can cause death, growth retardation, malformations, functional impairment and malignant diseases in childhood. These effects are strongly related to the developmental stage and the radiation dose. The 1st trimester is regarded as the period with the highest risk of cancer and malformations. At present there is considerable agreement, that doses of lt 1 rad would not have widespread effects on the developing embryo or fetus (BEIR III). Different commissions on radiological protection recommend to keep exposures below 1 rad, except when vital indications demand higher doses. The possibility of interactions between radiation and drugs, stress, diet, genetic and other factors adds a cautionary element to risk estimations. As consequences, unnecessary exposures of embryos and fetuses should be avoided and further information is highly desirable particularly at the low doses of interest for radiation protection.
Fritz-Niggli Hedi	Risks of health damage by ionizing radiation: Yesterday, today, tomorrow.	124-141 (2)
	The risks of health damage due to low levels of ionizing radiation are always embedded in the variation of the natural (spontaneous) rate of damage, in the variation of radiation exposure and the influence of additional noxes. The average of the radiation exposure (equivalent dose) for Swiss people is 250 mrem with a fluctuation from 138-436 mrem. Medical applications of 150 mrem are responsible for most artificial radiation exposure. Earlier assessments of possible risks of health damage due to low doses mainly considered the genetic damage, but nowadays studies of somatic risks are placed in the foreground. The effect of doses between 0.5-10 rem can only be estimated by interpolating different dose response functions. It is advisable to use the linear dose response model for radiation exposure estimates. The risk estimations for genetic and somatic risk have not changed considerably for 10 yrs.
Schneider F	Geometry and degree of resolution of an animal receptor of gravitational waves.	142-171 (2)
	After discovery of magnetic orientation of animals in 1957 additional experiments with cockchafers (Melolontha vulgaris F.) proved the great influence of terrestrial and cosmic masses on ultraoptic orientation and activity. This influence has the character of waves. Today's current meaning of the word gravitational wave has to be extended. The paper deals with the analysis of an animal receptor of gravitational waves (graviceptor) based on 72 photographs and 952 azimutal measurements (accuracy +- 0.5 degree ). The experimental results correspond with a graviceptor model composed of 6 mutually turned octahedrons. The graviceptor is dipped in the direction of the head. These 2 experiments prove again the capacity of animals to perceive exactly the directions of terrestrial and cosmic masses (walls, sun, moon) in spite of exclusion of any optic, magnetic, electric and electromagnetic information.
Ørn,Ch .G.	Development of wind conditions in the cold season from 1891 to 1982 and its effect on annual hypolimnetic oxygenation in Lake Zurich	172-180 (2)
	In the sub-alpine Lake Zurich (A = 65 km2, zMax= 136 m, z mean = 51 m) annual hypolimnetic reoxygenation begins during autumnal cooling and ends with summer stratification. A stable winter stagnation rarely occurs, so vernal circulation is normally found between January and March/beginning of April. Analysis of hourly wind velocities at the nearby meteorological station SMA Zurich since the year 1891 proved that wind activity in these months has decreased (fig. 1). Strong winds have become rarer. Previous studies have shown that winds > 20 km/h (wind velocity 4) are of particular importance for the wind-related oxygen increase in the hypolimnion of Lake Zurich. The decrease becomes even more apparent when estimating the wind energy working on the lake surface. Around the turn of the century energy sums totalling > 2 MJ/m2 of lake surface were calculated for numerous years (table 1). Since the beginning of the continuous limnological monitoring of Lake Zurich in 1936 they have varied from 0.04 MJ/m2 in 1964 - the worst hypolimnetic oxygen year - to 1.15 MJ m2 in 1970 - the best oxygen year for a long time. The second worst oxygen year occurred in 1963, when the lake was completely ice-covered from 24th February to 28th March. Deducting the winds recorded during the period of ice cover ("ice winds") only 0.03 MJ/m2 of wind energy remained to oxygenate the lake. As in 1964, the hypolimnion thus entered summer stratification burdened with a serious oxygen deficiency (table 2). From a limnological point of view the decreasing wind trend is a negative natural phenomenon. More wind action would favour turbulent uptake of atmospheric oxygen in the cold season.
Hotz Bolliger H	Morphology and behavior of the hirudinean, Haementeria steineri, new species.	181-206 (2)
	H. steineri sp. nov., discovered in Switzerland, was probably imported from the Brazilian Amazon region. They parasitize aquatic snails and appear to reproduce via parthenogenesis. The coelomic and circulatory morphologies are compared with those of Helobdella stagnalis (Glossiphoniinae). The new species is described and the genus is transferred from the Haemeuteriinae to the Glossiphoniinae. The comparative structures of the coelom and gut of Piscicolidae and Glossiphoniidae demonstrate that the latter is more primative.
Burgen,A.S.V.	Current aspects of synaptic transmission in the nervous system.	207-208 (2)
Müller,St.	Deep structure, dynamics and evolution of the Mediterran-Alpine region	217-245 (3)
	The geodynamic processes in the Mediterranean-Alpine region are primarily governed by the relative motion between the African and the Eurasian lithospheric plates. It presently results in a predominantly compressional regime leading to lithospheric shortening (of about 5 to 10 mm per year) and rifting in old, pre-conditioned zones of weakness. The boundary between these two major plates as defined by the recent seismicity is rather complex: it clearly extends all the way into the Alps due to the presence of the "Adriatic promontory" of the African plate. Thus a reasonable explanation is provided for the particular geographical location of the Alps and their deep structure as the consequence of a massive continent-continent collision which has led to a "delamination" of parts of the lithosphere, i.e. in particular "flaking" in the upper crust, combined with a thickening of the entire crust and the formation of a pronounced, relatively cold, dense, slowly subsiding "lithospheric root" beneath the mountain chain. In this still ongoing plate collision process the lower parts of the lithosphere apparently have penetrated the upper mantle to a depth of 100 to 200 km in a nearly vertical "zone of subfluence". On this scale the presently continuing uplift of the Alpine chain (by 1 to 2 mm per year) is a secondary effect due to isostatic rebound of less dense crustal masses which previously had been pushed to greater depths. A configuration of this type generates regionally a dynamics of its own on which - within a wider framework - rotational processes may be superimposed.
Straumann,N.	White dwarfs, neutrino stars and black holes	246-267 (3)
	The physics of the compact final states of stars has made remarkable progress since the discovery of pulsars in 1967. Because these end products of stellar evolution span an enormous density range, their analysis requires a deep physical understanding of the structure of matter and of the nature of interparticle interactions over a vast range of parameters. All fundamental interactions play an essential role in the formation, the structure, and the stability of compact objects. The modifications of the enormous gravitational field strength due to general relativity become quantitavely important for neutron stars. General relativity is indispensable for even a qualitative understanding of black holes. Neutron stars can be observed directly as pulsating radio sources and indirectly as X-ray sources (X-ray pulsars and X-ray bursters) and more recently as g-bursters. The opening of the "X-ray window" led also to the discovery of a black hole in the irregular, rapidly fluctuating source Cyg X-l. The energy source of quasars and other active galactic nuclei may involve accretion of matter onto supermassive black holes because this is the most efficient way to convert rest mass into radiation, and thus generate in a small volume the enormous luminosities observed from quasars.
Säuberli,H.	Surgical treatment of peptic ulcer	268-293 (3)
	Today vagotomy should be an integral part of every operation which is done by ulcer disease. Truncal vagotomy with pyloroplasty is because of its simplicity the preferred operation in complications (bleeding, perforation). For elective surgery vagotomy should be only selective, that means limited to the stomach. If the innervation of the antrum is preserved it is possible to do a proximal selective vagotomy without pyloroplasty. As a result of recent trials the result of proximal selective vagotomy (PSV) can now be judged with more certainty: The rate of recurrence is higher than after partial gastrectomy or combined procedures, but mortality is low and sequelae are rare. Recurrent ulcers after PSV usually have a good prognosis. It is not justified today to do as primary operation the resection or a truncal or a selective gastric vagotomy because mortality, morbidity as well as sequelae occur in a higher percentage of cases than in cases of a proximal selective vagotomy without drainage.
Gerber,E.K. & Scheidegger,A.E.	A chronical slide in argillaceous material	294-315 (3)
	Geomorphological processes are influenced by three factors: the topography (form), the material involved and the dynamic conditions. As an example of a geomorphological process, a chronic slide in argillaceous material in the Jura Mountains in the Canton of Aargau, Switzerland, has been investigated over a period of 18 years. It is shown that the properties of the material influence the course of the slide decisively: because a transition from solid to plastic and thence to fluid behavior has to take place, the slide occurs intermittently: short periods of activity alternate with long periods of quiescence. The active phases are triggered by heavy precipitation in winter combined with melting of the snow. A correlation-study shows that the precipitation causes motion at the fissures at the head of the slide after 1 day, in its upper part after 3-6 days, and at its bottom after 10-12 days. In this fashion, a complete dynamic model of the process is obtained.
Speiser,D.	Leonhard Euler, 1707-1783, Mathematiker - Physiker - Ingenieur. German	325-338 (4)
Bangerter U M	The occlusion of longitudinal wounds on the stem of Larix decidua and Picea abies.	339-398 (4)
	Histology and partly histochemistry were studied on specimens collected periodically from numerous simultaneously wounded 4 yr-old stems of larch and spruce. The immediate phenomena leading to wound occlusion were investigated as well as wound induced changes within the cambial differentiation pattern in the vicinity of the wound edge. On the average wound reactions start earlier and are stronger in Larix than in Picea. An histochemical barrier against pathogenic infections is effected by excretion of resin and by synthesis of polyphenolic compounds in parenchyma cells of that portion of the secondary xylem which is near the wound edges, and has been formed immediately before and after wounding. On the phloem side of the wound the barrier consists of a wound periderm which differentiates below a zone of lignified, dying tissue (wound bark scale). The tissue deficit caused by wounding is compensated gradually by 2 wound ribs which are formed near the cambial wound edge. These wound ribs consist of callus produced by the cambium and the wound phellogen. Cambial regeneration sets in from the edges of the remaining cambium by means of periclinal cell divisions in the callus. By the end of the growing season, the products of these divisions differentiate gradually into fusiform and ray initials. When the 2 wound ribs join there is fusion of the wound periderms as well as of the edges of the regenerating cambia bordering the wound.
Guyer,E.V.	Ein Querschnitt durch die Geschichte der NGZ in losen Folgen.	399-404 (4)

1983 128th.
Fierz,M.	On the Origin of Wave-Optics	1-20 (1)
	The picture physicists form of the origin and development of wave-optics contains several misunderstandings. In some measure they are due to the fact that the difference Newton introduced between descriptive "theories" and explanatory "hypotheses" was not taken seriously enough. Further one did not realize that the word "wave" had not the same meaning for Hooke and Huygens as it has today. In this respect Newton's sketch of a wave-theory is nearer to the modern view. But just because of his deeper insight he was baffled by a difficulty to which only Fresnel found a plausible answer, and only at the end of the 19th century was the question really cleared up.
Wildermuth,H. & Krebs,A.	Man-made Wetlands as Habitats for Dragonflies	21-42 (1)
	In Switzerland 58 % of the dragonfly species must be considered as endangered or are already extinct. The main causes for the qualitative and quantitative decline of the odonate fauna are pollution, change and destruction of the various larval habitats. Most of the endangered species inhabit natural or nearly natural biotopes. These dragonflies can only be protected by the conservation of the still existing remains of intact breeding sites. Investigations in the Swiss midlands show that odonata using anthropogenic wetlands (gravel pits, nature conservancy ponds, factory ponds and peat-diggings) for their propagation seem to have a better chance for survival, because those types of habitats are permanently reproduced. In gravel pits 39 species (31 certainly or probably breeding) were observed. Peat-diggings are colonized by 37 species (30 certainly or probably breeding). In garden ponds and nature conservancy pools 24 species were found (18 certainly or probably breeding), whereas the numbers in the factory pools is rather poor: 22 species, 8 certainly or probably breeding. The total number of species recorded in the four types of man-made wetlands was 43. Breeding was confirmed in 27 species and probable in 10.16 out of 43 species (11 certainly or probably breeding) belong to the category of endangered odonata. The dragonfly coenoses of the anthropogenic habitats are composed of more or less adaptable species. Presumably they inhabited the stagnant water bodies of the (now disappeared) natural stream valleys, bogs, ponds and lake shores. The conservation of the still existing populations dwelling in manmade habitats is only possible by protection, increase and suitable management of these sites.
Philipp,B.J.	Arnold Heim's unsuccessful oil exploration and successful water exploration in northeastern Arabia in 1924	43-73 (1)
	In the mid-twenties Arabia's rich oil deposits were still undiscovered. In 1924 the then university lecturer Dr. Arnold Heim (1882-1965) from Zurich, by order of the Eastern & General Syndicate, London, conducted an expedition with 60 participants, which served for the exploration of the oil and water resources in the geologically still little explored areas of Kuwait, al-Hasa (in present-day Saudi Arabia) and Bahrain in northeastern Arabia. After his two-months exploration, during which he and his work suffered from the summer climate of the Persian-Arabian Gulf region, he was convinced of the failure of future oil drilling, but of the success of future water drilling at some places in those areas. The results of his voluntary water exploration in Bahrain were exploited before long with great practical benefits. A second geological exploration in Arabia, which he aspired to during the following decade, did not materialize, and the Arabian journey undertaken in 1924 quickly fell into oblivion, although Heim took advantage of part of his research material by means of several magazine articles and lantern-slide lectures.
Schütz,J.P.	Emanations délétères, précipitations acides et dépérissement de forêts. (french only, summary of a symposium)	75-79 (1)
Tittmar H G	Gravity as a Zeitgeber: The mechanism.	81-88 (2)
	Gravity is not only a physical vector providing organisms with a spatial reference frame, but it may also be utilized to provide a temporal reference frame, thereby acting as a synchronizer. The mechanism inherent in this is traced to the Arousal I system of Routtenberg's Two Arousal Hypothesis. There may be no single center for the biological clock and sensing may not be continuous.
Klingler,J., Güntzel,0. & Kunz,W.	Xiphinema and Longidorus Species (Nematoda) on the Swiss Plateau.	89-114 (2)
	The distribution of the species of these genera was investigated systematically in vineyards and in apple orchards and sporadically in some other crops (e.g. strawberries). Three species of the genus Xiphinema were found: X. diversicaudatum, X. vuittenezi and X. index. (A fourth species, X. pachtaicum. originates from the Valais.) Of the genus Longidorus the species L. elongatus, L. macrosoma, L. profundorum, L. caespiticola and L. leptocephalus are present. Moreover there are two further species, resembling L. goodeyi and L. elongatus respectively. The localities of the finds of all the species are given in fig. 4-6. X. diversicaudatum shows a striking geographical distribution pattern: it is lacking in Eastern Switzerland and in the adjacent South German area (fig. 7), but occurs west of the basin of Walensee and Zu"nchsee and of the Limmat valley. The boundary line of distribution corresponds about to the line of touching between the Linth and the Reuss glacier during the time of maximum glaciation. L. profundorum preferably occurs in the fallow strips of modern apple orchards, which refers to a possible phytopathological significance. X. diversicaudatum, X. index and L. macrosoma were associated in several cases with the occurrence of NEPO-viruses on host plants. The relatively frequent finds of X. diversicaudatum, L. elongatus and L. macrosoma mainly occurred in sandy loam and somewhat less often in loam soil; the latter two species sporadically also in lighter and in heavier soils. L. profundorum prefers loam soil. The soils in which X. diversicaudatum were found were acid or neutral, those in which L. macrosoma and L. profundorum occurred, were clearly alkaline - apart from some exceptions.
Lienhard,Ch.	The Psocids from the Region of Zurich, Switzerland (Insecta: Psocoptera).	115-129 (2)
	Psocids predominantly belong to the fauna of forests, where they are inhabiting trees, shrubs and sometimes leaf litter. Several species are frequently found indoors and associated with human habitations. Psocids are generally feeding on microflora growing at these places. At present 60 species are known from the canton of Zurich, especially from the surroundings of the city of Zurich. For every species some information is given on its habitat preferences, phenology and abundance in this region. There are also made some general remarks on faunistics, phenology and ecology of these insects in this area. Densities of psocids (number of species and density of individuals) on different plant species and merotopes (e.g. living or dead branches) are remarkably similar. Beyond the often very clear preference for conifers or deciduous trees quite a number of species prefer also a particular merotope. Specializations in individual plant species are usually much less evident.
Schlatter ,R.	The Liassic ammonites described by Karl Mayer-Eymar (1826-1907).	131-134 (2)
	In an issue of diverse works, published in the years 1864-1875, Karl Mayer-Eymar described a number of badly known or completely new Jurassic ammonites. The systematics of the Liassic ammonites, listed therein, are treated in this paper. Under the new species described by K. Mayer-Eymar, Paracoroniceras militaris has to be emphasized.
Jost,R.	Walter Heitler (1904-1981).	139-141 (2)
Jost,R.	The Nature of Matter and Force: Emil du Bois-Reymonds World Model.	145-165 (3)
	Emil du Bois-Reymonds materialistic-mechanistic world view and his rejection of the German romantic "Naturphilosophie" are analyzed. A sketch of the development of Field-Theory starting with M. Faraday is given.
Lüscher ,H .R.	Self-organization as an ordering principle in the central nervous system	167-180 (3)
	Despite the fact that the reductive approach in neurobiological research has led to spectacular discoveries, more and more scientists believe that the orderly function of the brain cannot be satisfactorily understood from the analysis of its buildingblocks alone and their mutual interactions. In this paper an attempt is made to explain the highly ordered functioning of the brain as being due to a self-organizing process, the roots of which are found in the collective behaviour of large populations of nerve cells. In a first example a hypothesis is presented concerning the rhythmogenesis of respiration. By means of the Lotka-Volterra model the collective behaviour of a group of neurons making up the respiratory centers is described. In a second example it is proposed that the "size principle" of motoneuron recruitment is due to a self-organizing process during development of the connectivity between sensory nerve cells and motoneurons. This example illustrates how a probabilistic mechanism on the level of the single cell can lead to a deterministic behaviour of a large group of neurons.
Stranzinger,G.	Genetic engineering in animal breeding - present state and research.	181-194 (3)
	The article describes from different views the use of gene technology in animal breeding and genetics. Reasons for the use of gene technology in combination with genetic engineering in animal breeding are documented, with special attention given to aspects of world nutrition and the use of genetic peculiarities and resources. The mechanical complexity of the problem of the genetic manipulation of mammalian cells is visualized through selected examples which compare the genome size for viruses, bacteria and mammalian cells to each other. A description of natural and artificially produced chimeras in cattle, the development and existence of these animals and the biological consequences of chimerism give us a better understanding of the interference between gene transfer and other micromanipulation techniques. The exemplatory description of the gene transfer method should help to elucidate several mentioned general research activities in animal breeding, which can be seen as preliminary to the application of further advanced techniques.
Schanz, F. & Thomas E A	The Walenseeli, a small lake near Baech (Canton Schwyz (Switzerland)) connected with Lake Zurich.	195-205 (3)
	The Walenseeli is a small lake of glacial origin, connected by a channel 3 m deep and 50 m broad to Lake Zurich. The western part of the lake is 14.3 m deep; the eastern part is shallow. As a result of the lake's small surface area (0.104 km2) and of the fact that it is protected from wind by surrounding hills, the surface water warms up faster; thus a stable stratification forms earlier than in the adjoining Lake Zurich. The seasonal variations in O2, nitrate and phosphate concentrations in the surface water clearly show that the spring plankton bloom develops more intensely in the Walenseeli than in Lake Zurich. Hypolimnetic O2 conditions also point to the Walenseeli being more highly eutrophic than Lake Zurich: the hypolimnion of the Walenseeli is completely anaerobic at the end of the summer stagnation period, in contrast to Lake Zurich, where even directly over the sediments high O2 concentrations are found during the whole year. As a result the sediments of Lake Zurich are light gray in color; those of the Walenseeli are gray-black. No evidence of any influence of Lake Zurich on the Walenseeli can be found. The Walenseeli can be considered as a lake in its own right, independent of lake Zurich.
Pavoni, N.	Earthquakes and global tectonics.	213-231 (4)
	The belt of young fold mountains and the belt of active oceanic ridges represent the major tectonically active systems of the earth. They are clearly outlined by the distribution of earthquakes. Specialized seismological investigations give valuable information about the type and orientation of earthquake generating fault movements and therewith about the present state of deformation and stress in the crust and lithosphere of seismically active areas. In many regions of the Cenozoic fold mountain belt Switzerland included the present tectonic movements are in close relation or even direct continuation of neotectonic movements. They are part of large-scale continuous tectonic processes. Emphasis is given to a Pacific - anti-Pacific hemispherical symmetry in global tectonics which is apparent in the geotectonic evolution of the African and Pacific hemispheres during last 150 million years.
van der Waerden,B.L.	Models of dose-effect curves after irradiation	233-242 (4)
	For the evaluation of the risks of radiation damage it is important to know how the damage depends on the dosis. Three possibilities are considered: a linear function a pure quadratic function and a mixed "linear-quadratic" function. In the present paper a sequence of experiments on Drosophila are analyzed. The flies were exposed to small middle and large doses of radiation and mutations in the first generation were observed. A statistical analysis yielded the following results: 1. The most frequently observed mutations were caused by the loss of an X- or Y-chromosome. in these cases the results can very well be described by a linear function of the dosis. The deviations from the linear function are statistically insignificant. 2. Two kinds of partial chromosome loss were observed. In one of these cases a pure quadratic or linear-quadratic function could be appropriate. 3. In all other cases the number of mutations is too small to draw valid conclusions. The safest assumption is always a linear function. In all cases in which the mechanism of the damage is unknown one should assume a linear function.
Neuenschwander,E.	René Descartes and the Development of Modern Mathematics	243-281 (4)
	The present paper traces the development of modern mathematics from the end of the Middle Ages to the time of Leibniz and Newton. Part I begins by identifying a number of factors which played a decisive role in the emergence of the "New Science" and then goes on to present a brief survey of the main areas of mathematical research in the 16th and 17th centuries. Part 2 provides a more detailed examination of the development of algebra from the Greek "geometrical algebra" to the "symbolic algebra" of Viète and Descartes: it also investigates the transmission of knowledge between the various cultural eras and the first algebraic solution of third degree equations in Italy. Part 3 describes the creation of the calculus. In particular, the successive elaboration of methods of integration in the 16th and 17th centuries is illustrated by examples drawn from the works of Kepler, Cavalieri, Wallis, Fermat and Newton, and details are given of the Cavalieri principle, the various methods of differentiation in use at the time. and the dispute over priority claims between Leibniz and Newton. The paper ends with a brief consideration of Descartes contribution to these developments. and of the calculisation of mathematics during this period.
Fritz-Niggli, Hedi	Die Wirkung kleiner Dosen ionisierender Strahlen auf die Bevölkerung.	283 (4)
Thomas, E.A.	Edwin Messikommer (1891-1983).	285-287 (4)

1982 127th.
Max Waldmeier	Observation of the Total Eclipse of the Sun on February 16, 1980	1:1-18
	The eclipse was observed under ideal conditions at Yellapur (India). Two cameras were used, one of 50 cm focal length, the other one of 120 cm. During the totality 34 pictures were obtained for the study of the light distribution and the structure of the corona. The eclipse took place almost exactly at the time of the maximum of the solar activity. The same programme was carried out at the eclipse of October 23, 1976 which coincided with the minimum of the solar activity (Fig. 2). These two eclipses yield the material for a comparative study of the extreme forms of the corona (Fig. 4, 5, 7 and 11). At maximum the corona is twice as bright as at minimum and its isophotes are almost circular (Fig. 3). The different behaviour of the two hemispheres results from a phase shift, the development of the northern corona being ahead of that of the southern one by several months (Fig. 4, 6, 9 and 11). The streamers are nearly rectilinear but in general they deviate from the radial direction. These inclinations are of a systematic character, being strongest at the equator and the poles (Fig. 13).
Hansruedi Wildermuth, René Hantke und Jacques Burnand	The Drumlin Landscape of the Zurich Oberland	1:19-28
	The purpose of the annual excursion 1981 of the Society of Natural Sciences of Zurich was to look at the drumlin scenery near Wetzikon (BLN-Object 14.01) and the gravel-pit of Langfur-Gossau. In addition to the remarks given by the different guides in charge this report shows the geological and biological importance of this region and the reasons why it should come under protection.
Hans Heinrich Bosshard, Ladislav J. Kucera und Ursula Stocker	The Vessel System in the Prejuvenile Wood of Ash	1: 29-48
	The vessel system of ash (Fraxinus excelsior L.) is known to display a ring-porous arrangement in the juvenile and adult wood. In the prejuvenile phase, this typical pattern is not developed: Pores do not differ much in size nor are they ordered in closed tangential rows along the growth-ring boundary. In our three-dimensional investigations of the material we have measured a larger radial displacement of single vessels as compared with beech (Fagus silvatica L.). In this latter species the tangential displacement dominates. In oak (Quercus robur L.) we have found an accordance with ash. This tendency of a radial displacement of the vessels in the ring-porous species is even more pronounced through the presence of growth-ring bridges. As it has been shown by K. Ladefoged (1952) the cambial activity in ring-porous species starts earlier than the bud-break, in diffuse porous species later. Considering the special arrangement of the pores in prejuvenile wood we may state that the ring-porous pattern is not only a topographic fact but even more strongly one dependent on time.
Manfred Hesse	Chemistry in the Age of Enlightenment	1: 49-70
	After a short survey of the history of chemistry the author discusses how the development of the combustion theory in the 17th and 18th centuries changed chemistry from being dependent on other sciences to becoming a scientific discipline in its own right. Particular attention is paid to the phlogiston theory of Becher and Stahl and how it was disproved by Scheele, Priestley, Cavendish and especially Lavoisier. Modern chemistry was created in the Age of Enlightenment. Alchemistic tendencies which continued parallel to the scientific ones at that time are briefly mentioned at the end of the paper.
Bosshard, H.H.	... Hr. Doctor juris Göthe von Frankfurt	1:71-78
Rieber, H.	Das Paläontologische Institut und Museum der Universität	1:79-80
Thomas, E.A.	Die hydrobiologisch-limnologische Station der Universität	1:81-83
Ernst Ott	Morphological and Physiological Ageing of Secondary Phloem in Larix decidua Mill.	2: 89-166
	The secondary phloem of young European larch was investigated microscopically and histochemically. Shortly after the loss of their functioning capability, the sieve cells collapse whereby the sieve areas and the thickness of the cell walls do not change actively. Their percentage area in the tissue is reduced from 70 to 8% within three years through subsidence of the tangential walls and the folding of the radial walls. The axial and ray parenchyma cells increase their percentage in the tissue from 21 to 64% by growing and rounding off of their shape. Stored starch is dissolved not only in the Strasburger cells which collapse at the same time as the sieve cells but also in the young sclereids before they incrust their secondary walls with lignin. The thinly-walled fusiform crystalliferous cells adjust their shape to a large extent to the growth movement of the surrounding tissue. Intercellular spaces originate schizogenously and constitute nearly 20% of the tissue in three year-old, transversely-sectioned phloem. The histochemical localization of peroxidase and b-glucosidase activities indicates that these two enzymes not only participate in the synthesis of lignin but may also play a role in the active expansion of the cell wall. The observation of the succinic dehydrogenase and cytochromoxidase activities reveals that the sieve and the Strasburger cells die together at the latest one year after their differentiation. The acid phosphatase is detectable mainly in sieve and phloem ray cells, which serve as conductors of assimilates.
Gerhard Zbinden	Promotors, Chemical Pace-Makers of Carcinogenesis	2:167-176
	Promotors are substances which do not cause cancer but have the ability to stimulate growth of cancerous ("initiated") cells. The various biological properties of these agents were mostly investigated with the help of the mouse-skin model. The possible relevance of the promotors for human carcinogenesis is discussed.
Vincent Ziswiler	Biology in the Period of Enlightenment	2:177-191
	If; by the period of enlightenment of a science, one understands its rational infiltration as being based on an empirical foundation, then one can easily see how the period of enlightenment in biology and the classical enlightenment of the time coincide. The voyages of discovery and the invention of the microscope opened up new horizons in biology in the 17th century. Besides the purely descriptive salient points and the cataloguing of living creatures and their essential parts, there was more and more intellectual interpretation of biological phenomena, whereby the methodology and axioms of the empirical and rational philosophers stood the scientists in good stead. Preferred subjects of discussion during this enlightenment period were the theory of conception, the search for a natural order, the question of the variability of species and the interpretation of fossils.
Wydler,P.	Lärmbekämpfung - ein vordringliches Problem.	2: 193-195
Urbanska, Krystyna M.	Lebensstrategien der Pflanzen von semiariden Ökosystemen Nordamerikas	2:196
Kahle, Hans-Gert	Moderne geodätische Messtechniken und ihre Anwendungsmöglichkeiten in der Geodynamik	2:196-197
Dressler, Kurt	Moleküle im Weltraum - Molekularspektroskopie	2:197
Gerhard Zbinden	Promotoren, chemische Schrittmacher bei der Krebsentstehung	2:197
Hünermann, Karl A.	Tropische Säugetiere als Zeitmarken im Tertiär des Zürcher Raumes	2:198
Anliker, Max	Biomedizinische Technik an den Zürcher Hochschulen	2:198-199
Rybach, Ladislaus	Geothermische Energienutzung in der Schweiz - Möglichkeiten und Grenzen	2:199-200
Scherrer, Kurt	Die Satelliten-Bodenstation Leuk	2:200
Landolt, Elias	Dr.h.c.Walter Höhn-Ochsner (1885-1981)	2:203-204
Niederer, Ueli	Galileo Galilei and the Rise of Physics	3: 205-229
	After a short review of the life of Galileo (1564-1642) two of his principal scientific works are discussed. The Sidereal Messenger (Sidereus Nuncius, 1610) is important not only because it contains the first historic results of observations of the sky with a telescope, among them the discovery of Jupiter's four moons, but also because it clearly shows the objective and openminded attitude of Galileo as a scientist. In the Discourses (Discorsi, 1638) Galileo created the theory of motion as a pure kinematics. Starting from the basic law according to which the natural fall of a body is a uniformly accelerated motion, he developed his theory of fall and projectile motion mathematically and confirmed it by experiments on the inclined plane. The importance of Galileo however goes beyond his individual results because he put science on a new basis and set new goals. His science is characterized by three elements: mathematization, experiment and abstraction. His scientific method which proceeds through the steps of hypothesis, deduction and confirmation unites the three elements to the physics we know and of which he was a founder.
Kurt Eiberle, Jean-François Matter und Othmar Wettmann	On the Population Development of field Hare in the Canton of Zurich (Switzerland)	3: 231-245
	The purpose of the present investigation was to assess the influence of air temperature and precipitation on the annual kill results of field hare (Lepus europaeus) in the canton of Zurich in the period of 1930 to 1979. The investigation showed that the influence of the weather factors at different seasons varies with the length of time involved and that the monthly meteorological values show more pronounced dependencies than seasonal values. Air temperatures were of decisive importance for the population development of the field hare during the reproductive season. However, the long-lasting consequences of mild winters too were particularly important since such winters encourage the outbreak of coccidiosis. Precipitation played merely a subordinate role within the given general climatic conditions. A combination of the relevant weather elements made it possible to explain the actual kill development with a remarkably high coefficient of determination of 87 percent.
Hans-Niklaus Müller	The Lateglacial Advances of Gondo and Zwischbergen (Simplon, Valais, Switzerland)	3: 247-255
	Moraines in the Zwischbergental (Simplon, Valais) allow the reconstruction of former glacial surfaces. From this the lowering of the corresponding equilibrium line altitudes in relation to a mid-19th century datum level can be calculated. This reveals a series of glacial advances between the mouth of the valley at Gondo and the modern glaciers at the head of the valley, covering the timespan from the Lateglacial until the mid-19th century maxima. The lowering of the equilibrium line altitude of the largest glacial advance amounts to 660 m as compared with 1850. To this advance the local name «Gondo-Advance» is assigned. It is the correlative to the Gschnitz-Advance of the Eastern Alps. Deposits of prominent advances can be found between the Gschnitz-Advance and the Daun-Advance to which the local name «Zwischbergen-Advance» is assigned. The lowering of the equilibrium line amounts to 500 m as compared with 1850. The criteria for the delineation of the Zwischbergen advance are similar to those which were used for a subdivision of the GschnitzAdvance in the older literature.
Max Schüepp	New Development in Weather forecasts	3: 257-271
	Development in the field of weather forecasts during the past 50 years is analysed. Several changes have taken place. New technical aids have been introduced: Observation of cloud systems by satellite, precipitation areas by radar and currents in the free atmosphere by radiosondes and other instrumental methods, e.g. equilibrated balloons. This material and the Swiss automatic weather stations have improved the medium range forecasts of modern computers considerably. The development should lead to a change in the nature of forecasting work: More persons will be engaged in research, fewer in the daily service.
Gutermann,Th.	Internationales Feldexperiment ALPEX.	3: 272
Wanner,H.	Eugen A.Thomas. Zum siebzigsten Geburtstag 19.November 1982.	3: 277-279
Sven Björk	Exploitation, Protection and Management of Tropical Wetlands - Examples from Jamaica	4: 281-298
	A plan for peat extraction is being developed for the Negril (23 km2) and Black River (71 km2) morasses in Jamaica. The preparatory work for the project is organized in such a way by the Jamaican authorities that extraction plans are designed in a joint cooperation between ecologists and engineers. The Negril morass was badly damaged due to water level lowering in 1959 and the Black River morass is threatened by a series of interferences. Investigations carried out so far clearly indicate that peat extraction offers possibilities to rejuvenate the morasses as wetlands with a mosaic structure. The ecological preinvestigations include palaeoecological studies, chemical and physical water and peat analyses and a detailed mapping of the organism communities. Furthermore experiments concerning structural and functional development of marsh ecosystems are carried out in lakes and ponds dug out in the peat.
Clifford H. Mortimer and Wilfried Horn	Internal wave dynamics and their implications for plankton biology in the Lake of Zurich	4: 299-318
	Knowledge of wind-induced displacements of water layers in the Lake of Zurich, the subject of 1949-1951 observations by E. A. Thomas, has been recently extended by multi-position and multi-depth records of flow and temperature obtained during August and September 1978 by the "Versuchsanstalt für Wasserbau, Hydrologie und Glaziologie", ETH, Zurich. The large body of new data, thus acquired, is still being analysed. Some of the principal findings, relating to internal seiches and internal surges, are described here. E. A. Thomas also showed that the storm-induced displacements of the lake's layers from equilibrium had strong repercussions on the water chemistry and plankton biology of the lake. That discovery is taken here as a point of departure for speculation on probable interactions between plankton population dynamics and on the hydrodynamic events and mechanisms disclosed by the 1978 study. Particular emphasis is laid on the current shears produced by the to-and-fro passages of internal surges (travelling as waves of depression along the thermocline interface) here seen and described in detail for the first time in the Lake of Zurich. If' after strong wind, the surge amplitude is large enough, flow in the neighbourhood of the thermocline will become temporarily unstable, i.e. when the local value of the Richardson number falls below the critical value of ¼. Vertical mixing by turbulence will suddenly increase; this will disperse any plankton populations which are congregated (as often happens) in or near the thermocline; and a pulse of nutrient-rich subthermocline water will be injected into the often nutrient-starved layers above. Evidence from the 1978 findings suggests that this type of instability is very likely to occur, during the stratified season in the Lake of Zurich, whenever strong currents are generated by wind action or by the passages of the internal surges, which follow after the wind impulse has subsided. The question of whether the surges are reflected at the basin ends or generated anew by each strong downstroke of the thermocline is still an open one. The Zurich results suggest that the latter mechanism is important.
Roland Pechlaner	Limnological requirements in protective hydro-engineering	4: 319-336
	In connection with the hydro-engineering measures entailed in flood control there is an increasing awareness of the necessity for planning and constructing in a manner aimed at preserving the valuable ecosystems involved. Unfortunately, there is still too great a discrepancy between what an engineer understands by nature-oriented water technology and what could be achieved if the limnological specifications of each stretch of water were to be taken into consideration at the planning stage. This discrepancy must be reduced at the earliest possible date if the ecological requirements and technical alternatives are to be combined to produce the optimum solution for the environment. In the hope of promoting interdisciplinary cooperation, the significance of some important milieu factors (current mosaics, temperature and chemistry of water, light climate) on the diversity and unhindered development of the plant and animal species, on the ecological equilibrium, self-cleansing, recreational value and fish yield of mountain streams and rivers in the Alps will be considered. In addition, certain problems raised in discussion by hydro-engineers, with regard to river bed stability, redisposition of bottom sediments, optimization of methods of step-like regulation, preservation of meanders and the best type of cross section for the construction in question are commented upon from the limnologist's point of view. To ensure that adequate attention is paid to the vast complexity of factors and situations encountered in aquatic ecosystems the collaboration of trained specialists whose professional, full-time occupation lies in the field of limnology is essential. The consistent employment of suitably qualified limnologists is a vital necessity in the planning and execution of every project involving hydro-engineering of inland waters.
Pierre-André Tschumi, Bruno Bangerter, Daphne Zbären	Ten Years of Limnological Research on Lake Biel (1972-1981)	4: 337-355
	At the beginning of the century lake Biel was still oligotrophic. After 1930 its trophic state changed rapidly and since the sixties the lake has been eutrophic. The very high nutrient loadings (153 g/m2. a N03-N and 22.5 g/m2 a Pt0t) are related to the fact that since 1878 the river Aare has been diverted into the lake. This increased its drainage area 2.6 times. Between 1972 and 1981 the phosphorus loading and concentrations have markedly decreased due to improved sewage treatment. However, gross primary production rates remained unchanged (400 g/m2. a C) as also the hypolimnion oxygen consumption rates (2000 mg/m2. d). From 1973 to 1981 no release of phosphorus from the sediment could be detected. Phosphorus is incorporated into the sediment at a rate of 6 g/m2. a. Phytoplankton biomass and composition change in the course of the year and from year to year. After the spring algal bloom, a drastic reduction occurs regularly in early summer accompanied by increased water transparency. Low radiation and high runoff may contribute to this phenomenon. However, the main cause seems to be grazing by the zooplankton. Until now the rotifer and crustacean plankton have been studied. In 1974 and 1978 the crustacean annual production was 40 g/m2 of which 23 g/m2 were lost in the outflow.
Ferdinand Schanz	Light conditions in Lake Zurich 1979-1981 Part I: Secchi disk transparency	4: 357-367
	In Lake Zurich weekly measurements of Secchi disk transparency were made over a period of three years, from 1979-1981. Simultaneously the light intensity and the dry weight of suspended matter were determined at several depths from the surface down to 20 metres. Periodically chlorophyll a concentrations were also measured. Based on all available data, five periods with similar properties of transparency can be distinguished during the year. The daily oscillations of light energy have only a moderate influence on the transparency. At a Secchi disk depth of 2 metres 22 % of the subsurface light intensity was measured, at 12 metres 3 00. The exponential decrease found is a result of the decrease in the concentration of suspended particles which gives rise to less intense occultation and light scattering. An exponential relationship between transparency and total extinction coefficient was found. Based on the data presented in this paper, a theoretical maximum in the Secchi disk transparency was estimated to be 25 metres.

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