Showing papers in "Naturwissenschaften in 1976"

Lichens as Indicators of Air Pollution

Abstract: Lichens are well known as sensitive indicators of air pollution, particularly for sulfur dioxide. In part, this is related to their unique biology. Evidence supporting this assertion goes back well over 100 years and is based on extensive field and laboratory studies. In general, these studies reinforce each other, but for oxidants the data are not entirely consistent, and consequently require further work. At the least, lichens appear to be less sensitive to oxidants than vascular plants. Acid precipitation effects are closely related to SO2 effects. The mechanistic basis for SO2 effects is briefly reviewed. The extreme sensitivity of lichens to SO2 is partially related to their ability to absorb more SO2 for a given concentration than typical vascular plants. The use of lichens as long-term integrators of elemental deposition patterns is well established, but their use for monitoring dry deposition has only recently been recognized. Air pollutants adversely impact not only growth, reproductive potential, and morphology, but also a wide variety of physiological processes, which also becomes reflected in ultrastructural changes. The impact of organic pollutants on lichens is largely undocumented and is a prime area for future work, even though much work remains to be accomplished with the traditionally recognized air pollutants.

The aggregation pheromones of bark beetles: Progress and problems

Abstract: Bark beetles (Coleoptera: Scolytidae) are insect pests inhabiting the subcortical tissues of trees. They account for much of the timber losses in coniferous forests throughout the Northern Hemisphere. Destructive outbreaks have been recorded in the past and present alike as soon as windstorms, drought, flood, root competition, or defoliation impair tree health and provide suitable host material for exploding beetle populations. Attacking en masse, aggressive populations overcome their host trees regardless of health or vigor. What appears to be attack by brute force, however, is actually the outcome of an intriguing system of chemical communication which in many respects resembles that of social insects more closely than the sex pheromones of lepidoptera. The elements of scolytid communication are host-produced volatiles as well as insect-produced pheromones; the response is not truly sex-specific, with both male and female beetles aggregating [1]. This ensures the utilization of temporary habitats [2] such as broken limbs or lightning-struck trees, providing an obvious mechanism for survival of endemic populations. But the same mechanism may mark resistant trees for simultaneous mass attack when and where epidemic populations prevail. Consequently, the term \"population aggregating pheromones\" or briefly \"aggregation pheromones\" (Populationslockstoffe) was introduced to emphasize the pheromonal function in host colonization. This is not to overlook the fact that aggregation of both sexes leads to the encounter of a mate. Nevertheless, the target marked by bark-beetle pheromones is the host, in contrast to the sex pheromones, where it is the mate. The fact that bark beetles are attracted to, and aggregate on, suitable host material has been commonly known for centuries and was used empirically in Europe to combat the pest with \"trap trees\". Gmelin [3] described such procedures in his remarkable essay \"Abhandlung fiber die Wurmtrocknis\" as early as 1787. However, Anderson [4] was first to prove the existence of attractants experimentally in 1948 and another decade passed before research investigated this phenomenon systematically [5]. The experimental proof that beetle-produced volatiles are involved in bark-beetle attraction was followed by the first successful identification of three terpene alcohols [6] in 1966. Since then, considerable progress has been made in the identification of aggregation pheromones and related structures, as well as in the biosynthesis of such compounds and the insect's response behavior. Aggregation pheromones are thought to occur throughout the family of Scolytidae with a few possible exceptions [7]; but there are many bark-beetle species which respond most readily to resinous materials exuding from damaged or infested timber as, for example, Blastophagus piniperda [8]. In general, the beetles emerge from a brood tree or overwintering site and disperse in search of new breeding places. Random dispersal and close-range host recognition, which may include olfactory response to host odors (primary attraction), are considered instrumental. Invariably, the beetle initiating gallery construction selects the host. In monogamous bark-beetle species, this is the female; among polygamous beetles, the male. As they enter the bark, pheromones are released usually by defecation, and/or host volatiles are activated. Colonization starts in response to this strong and specific secondary attraction, which increases as more beetles enter the same host and generate more of the attractive principle (Fig. 1). During this stage of attack, the focus of attraction may extend from a part of a tree to the whole, and from several trees into an attractive area in which beetles aggregate for mutual attack of additional hosts. Many Dendroctonus and some Ips spp. are capable of marking new host trees in spite of copious resin flow which prevents the beetles from feeding. Such \"contact pheromones\" are appar-

Initiation of protein synthesis.

Abstract: Protein synthesis is the last step in expression of genetic information. In this step, messenger RNA is translated to yield a polypeptide chain whose amino acid sequence is determined by the nucleotide sequence of the messenger. There are three steps in translation: initiation, elongation, and termination. Chain initiation and the beginning of chain elongation are schematically represented in Figure 1. In prokaryotes the mRNA is first bound to the small ribosomal subunit. This is followed (step 1) by binding of the initiator aminoacyl tRNA to the small subunit-mRNA complex. This step requires Mg 2+, initiation factors (IF), and GTP. Next, the larger ribosomal subunit joins this complex to form the initiation complex proper (step 2) and the stage is set for chain elongation. The second aminoacyl-tRNA is bound in a reaction (step 3) that requires GTP and an elongation factor (EF-1) whereby GTP is hydrolyzed to GDP and Pi. The first (initiator) and second aminoacyl-tRNA occupy sites on the ribosome designated as the peptidyl (P) and aminoacyl (A) site, respectively. Peptide bond formation takes place (reaction 4); the A site now bears dipeptidyl-tRNA while the P site bears the deacylated initiator tRNA. In the next (translocation) step (step 5)the ribosome is displaced relative to the messenger-peptidyl tRNA complex; the initiator tRNA is ejected and the peptidyl tRNA is now on the P site. This sets the stage for binding of the third aminoacyl tRNA and these processes are repeated until the polypeptide chain is completed. Translocation requires a second elongation factor (EF-2) and one more GTP which is hydrolyzed to GDP and Pi. Whereas the steps and mechanisms of protein syn-

Lake sediments as indicators of heavy-metal pollution

Abstract: Heavy metals are one of the most toxic forms of environmental pollutants, constituting a threat both to aquatic life and the quality of drinking water. By analyzing lake sediments, it is possible to determine the provenance, distribution, extent, and also the possible hazards of metal contamination. Sedimentary cores, in particular, provide the means for evaluating the different influences from natural and civilizational sources; they represent a historical record of the metal accumulations which have taken place during the past decades as a result of population growth and industrial development.

Spurenanalyse der Elemente —Zahlenlotto oder exakte Wissenschaft?

Abstract: In many disciplines, research and technological progress is often inconceivable without analytical information as to the material of interest. This situation has rapidly led to contradictory considerations of the problems by producers and consumers of analytical data; this is true especially in cases, where extreme limits of detection are required. After a discussion of recent problems, some experimental solutions in the field of \"analysis of purest materials\" are described, which should strengthen confidence in analytical chemistry and lead to a more efficient cooperation with other essential neighbouring disciplines.

Ultrasonic relaxation spectroscopy in liquids

Abstract: Ultrasonic techniques have been widely applied for material testing and also in the field of medical diagnostics, substituting X-rays for the visualization of tissues and organs. However, in fewer cases ultrasonic waves have been used to determine chemical properties of substances; ultrasonic measurements have contributed the earliest results in fast chemical kinetics in liquids with relaxation times r< l /gs , i.e., the time range of elementary processes such as protonation, solvation, and hydrogen bonding. Following the fundamental work of Nernst, Einstein, Herzfeld, Kneser, Bazulin, Meixner, Tamm, Eigen, Lamb, and others, the theoretical and experimental aspects of ultrasonic relaxation techniques have been treated in a number of comprehensive publications [1-16]. Therefore this short paper only intends to give a brief report on ultrasonic technical developments in our laboratory during the last years, including some illustrative kinetic examples.

Spectral sensitivities and photopigments in adaptation of fly visual receptors.

Abstract: Chromatic adaptation and receptor-deficient mutants have been used to systematically eliminate specific receptor function to provide the first complete spectral sensitivity and photopigment characteristic data of all three receptor types (R1-6, R7 and R8) in Drosophila compound eyes. Different fly genera have different adaptation responses which allow characterization of photopigment spectra. Drosophila mutants with anomalous excitation also reveal mechanisms coupling photopigment activation with receptor excitation.

Model consideration for the origin of life

Abstract: In an attempt to understand the origin of living systems we encounter the following problems: How can we conceive the origin of the first self-reproducing forms, and by means of what stimuli could a constant increase in the complexity of such forms commence? How can a translation apparatus for genetic information develop? One cannot that such an apparatus for the synthesis of enzymes can function alone without the interference of enzymes themselves, which, however, could only become available after the construction of the apparatus itself. What stimulus mechanism is conceivable that leads to the division of the genetic apparatus into a replication system, and an enzyme-synthesis system? The main problem therefore, is not the search for basic theoretical concepts. It is not a question which can be answered by means of specific experiments. One should rather explore the principal possibilities of how molecules combine to produce more and more complicated functional units. We look for the fundamental structural changes in the organizational systems and the driving forces initiating these developments. Questions concerning the detailed chemical realization are of secondary importance. In trying to solve the puzzle of how the genetic apparatus is gradually built up as complex aggregates of molecules, we consider a consistent causal chain of simple and transparent physicochemical model steps. The driving force for the self-organization of matter is seen in a specific environmental structure to be found on the surface of the earth. By this structure, which is periodic in time and heterogeneous in space, evolution is initiated and driven towards a continuously increasing degree of complexity correlated with a continuous expansion of the accessible living space. This process is a necessity under proper environmental conditions. Accidental events initiate each step but do not determine the general course of evolution which is determined by the selection mechanism.

Tidal growth patterns in recent and fossil mollusc bivalve shells: a tool for the reconstruction of paleotides

Abstract: Growth patterns in living intertidal and shallow-subtidal bivalve shells record tidal fluctuations of sea level. Organic lines correspond to low tides and inorganic layers are deposited at flooding tides. From this record it is possible to reconstruct tidal curves. Tidal growth patterns are distinguishable from other types. Fossil growth patterns can be used to determine the tidal curves of paleoceans and paleoseas. The tidal curve of the Upper Maestrictian Interior Sea of U.S. is presented as an example. The proposed reconstruction shows a mixed predominantly diurnal tide similar to that of today at Galveston (Texas) or in the Caribbean Sea during Fox Hill Time in South Dakota.

Lysimachia: Ölblumen der Holarktis

Abstract: Aggregation of the southern pine beetle, Dendroctonus frontalis Zimm. (Coleoptera: Scolytidae) on loblolly pine (Pinus taeda L.) under beetle attack was not disrupted by aerial applications of \"Frontalure\", a mixture of the attractant pheromone frontalin and the host terpene c~-pinene. Instead, aerial saturation with the pheromone in a heavily beetleinfested pine forest resulted in a rapid increase in the aggregation of beetles on pine trees undergoing attack. Previous work has shown that some disorientation of endemic populations can be effected by attracting the beetles to a source or numerous competing sources of synthetic attractants, particularly in the absence of naturally attacked trees. The experiments reported here were designed to determine whether the theory of \"disorientation\" or \"communication disruption\" [1] might be applicable to keep epidemic D. frontalis populations from aggregating on host trees that were under natural attack. 230 kg of rice seed soaked with Frontalure [2] were applied by aircraft equipped with a rice spreader over a 10 ha section of pine forest including an actual D. frontalis infestation of ~ 1.6 ha. The test area, marked by balloons, was evenly seeded with rice which penetrated the canopy well, releasing approximately 86% of the Frontalure during the first 3 h, and 96% within 24 h. One hardware cloth sticky trap 30 x 30 cm was placed on each of five naturally attractive pine trees under attack by the beetles and on each of five non-host (broadleaf) trees. The latter were baited with two plastic caps containing enough Frontalure to release racemic frontalin (99%) at an estimated rate of 2 mg/h and trap. Aerial applications of Frontalure-soaked rice were made in the early afternoon before the daily peak of beetle flight occurred. Beetles caught on the traps were removed at noon each day before and after aerial treatments. A preliminary application of Frontalure amounting to 45 g frontalin per ha clearly reversed the pattern of beetle catches. The majority of beetles was caught on the baited traps before the aerial application, but on the unbaited traps afterward; However, suppression of beetle response to the Frontalurebaited traps was not complete, probably due to insufficient pheromone saturation of the area throughout the test period. A second aerial application of Frontalure-soaked rice representing 450 g frontalin per ha almost completely interrupted the beetle response to the Frontalure-baited traps on the broadleaf trees. This treatment resulted in heavily increased beetle catches on the pine trees that were undergoing attack. During the 24-h period prior to the application, both sets 100-

Capsule shedding in tetrahymena.

Abstract: formed after spraying. Again many branches at 100 ppm and some at 30 ppm were stunted. The effect of chlorflurenol was persistent because growth retardation of stunted branches continued for at least 4 months after spraying. Application of 10 ppm spray to these two cultivars resulted in 2 to 3 times as many new normal shoots as on control plants indicating that chlorflurenol sprays of about this concentration could be used to increase branching in evergreen azaleas. Higher concentrations should be avoided because of the undesirable side effects of leaf curling and growth retardation.

Molecular sensory physiology of Euglena

Abstract: After a short description of the motile physiology of Euglena gracilis the responses to light stimulation are analyzed and a new nomenclature is proposed concerning flagellar motility variations. A discussion follows about the characteristics of the photoreceptive system of Euglena and about the flavinic nature of its phototactic pigments.

Circannual cycle of circadian cycles in a golden-mantled ground squirrel.

Abstract: (a) (b) (c) The presence of granules and associated swellings in the nascent microfibrils was confirmed by observations of replicas of freeze-etched pellicles (Fig. l c ; see also Fig. 4 of [5]). The foregoing observations are not consistent with the notion of extension of the microfibril by a progressive addition of monomers to the tip of a fully consolidated thread because such a manner of elongation would push the granule aside rather than enclose it completely within a sheath. On the other hand the observed occlusion of foreign granules by the microfibrils of a range of sizes is easily understood if it is assumed that previously synthesized macromolecules associate by London forces to form the strands and in so doing occasionally trap a particle from the medium. All these observations are fully explained by the assumption that the microfibrils are formed by progressive association of the molecules of a polymer(s) in an incipient gel, first to form a mesh of

Zur Verwendung von Mikroalgen für Ernährungszwecke

Abstract: Mass cultures of planktonic microalgae can render large quantities of proteinaceous matter. The good nutritional quality of microalgal protein has been proven both for animals and for human. The toxicologic safety of microalgal biomasses is, however, not yet sufficiently established. This requires further toxicologic studies, before cultivated mocralgae can commercially be utilized as ingredients of animal feed, or as food additives. Both types of nutritional application may become economically feasible.

Cell polarity in root statocytes in spite of simulated weightlessness

Abstract: tions at room temperature significantly lowered the response of soybean callus t o both zeadn and kinetin. Up to 90% of biological activity was lost at low and intermediate cytokinin levels, as indicated, for example, by the response to 0.3 gg of zeatin. After treatment, biological activity was equivalent to approximate!y 0.03 lag. It seems highly likely that cytokinin degradation has occurred by processes similar to those recorded by Sachs and co-workers [1]. Irrespective of the nature of the losses, it is obvious that the reduction of volatile eluates, from paper chromatograms for instance, should not be carried out by the methods described. Even if reference standards are treated in the same way, the uncontrolled nature of the reduction process is likely to lead to quite severe underestimates of cytokinin activity in plant extracts. In the experience of the author, this contribution to cytokinin loss following chromatography of plant extracts can be avoided by the common practice of incorporating the relevant pieces of chromatography paper directly into the assay medium, rather than eluting activity from the paper before bioassay. However, it still remains to be established whether similar degradative losses also take place on the actual chromatograms during the evaporation of the chromatographic solvents.

Queen substance bei eierlegenden Arbeiterinnen der Honigbiene ( Apis mellifica L.)

Abstract: We are most appreciative for the stimulating atmosphere at the University of California which enabled this project as a genuine combination of teaching and research and the fruitful interaction of students and faculty as part of a regular class. We are especially thankful for the generous contribution of computer time and a grant by the Committee on Teaching. Received June 29, 1976 l . Agrell, S.O., Bown, M.G., McKie, D.: Amer. Mineral. 50, 278 (1965) 2. Wenk, I-I.-R.: ibid. 59, 86 (1974) 3. Lopes-Vieira, A., Zussman, J.: Mineral. Mag. 37, 49 (1969) 4. Main, P., Woolfson, M., Germaine, G.: MULTAN, unpublished computer program 5. Zalkin, A.: FORDAP, unpublished computer program 6. Busing, W.R., Martin, K.O., Levy, H.A.: U.S. Nat. Tech. Inform. Serv. ORNL-TM308 (1962), computer program NUCLS6, modified version 7. Eggleton, R.A.: Mineral. Mag. 38, 693 (1972)

The plasticity of the mammalian central nervous system with special reference to new growths in response to lesions.

Abstract: Soon after birth all generation of neurones ceases. Thereafter neuronal death takes over. We have the gloomy prospect of having inherited a brain that is progressively degenera t ing-a t least in its neuronal population. In special areas remarkable death rates occur apparently as a regulative process for neuronal populat ions that grew in excess of needs in the intial neurogenesis. For example, Cowan [1] reports that in the isthmo-optic nucleus of the chick 27000 is reduced to 11000 in a few days and in the mesencephalic nucleus 4000 reduces to 1000. In the toad Hughes [2] and Prestige [3] find a great neuronal loss in the spinal cord particularly in the motor columns. The control of neuronal death is not known nor is the basis of sparing. Presumably the neuronal multiplication in the earlier stages results in an excess of neurones and far beyond the needs of the matured neuronal system, hence the control of population by death. These are dramatic cases, but throughout the life of mammals and man there is a continuous neuronal death. Brody [4] reports that there is a continual loss of neurones in the male frontal cortex. For example the population at 40 years is reduced to half by 90 years. But fortunately, as we shall see, progressive death is not the whole story.

1,3-Dimethyl-2,9-dioxabicyclo[3.3.1]nonane; A host-specific substance in Norway spruce under attack by Trypodendron lineatum Oliv.

Abstract: The isolation and identification of the title compound was carried out in the following manner: Twenty kilograms of the bark from T. lineatum-infested Norway spruce were collected and put directly into pentane after the entrance holes of boring beetles were thoroughly cut out. After standing for 72 h at room temperature the solvent was removed through a 1-m Vigreux column and the residue was distilled under N z at 15Torr. All volatiles up to 100 ~ were collected, yielding 5.2 g of mainly monoterpene hydrocarbons, oxidized monoterpenes, and sesquiterpene hydrocarbons. GLC analysis was carried out on a Carto-Erba 2100, using a 50-m stainless steel capillary column with Marlophen 87 under program from 50 to I40 ~ at a rate of 3 ~ mass spectra were obtained from a Varian MAT 111 GCMS coupling system. A trace substance (0.2Zo) eluting between 7-terpinene and terpinolene furnished a mass spectrum which strongly resembled the known 1-methyl-6,8dioxabicyclo[3.3.1]octanes [1, 2]: 43 (100), 54 (11), 55 (12), 58 (22), 67 (11), 68 (16), 71 (26), 81 (12), 87 (40), 114 (28), 156 (6, P). Preparative GLC on a Carlo-Erba 2400 with a stainless steel column (8 m, 8 mm i.D., 10% PPG on Chromosorb G AW-DMCS 60-80 mesh) yielded 0.2 mg of the substance, the IH-NMR spectrum (Bruker WH 270, 15,000 scans) of which showed two characteristic signals at b 4.09 (1 H) and 4.21 (1 H), suggesting a bicyclic ketal structure together with the molecular formula C9H1602, obtained by high-resolution mass spectrometry (Varian MAT SM 1). None of the probable 6,8-dioxabicyclo[3.2.1]octane structures which were prepared for comparison were completely in accord with all data of the natural compound. But 1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nouane, a ketal belonging to a bicyclic system recently found in tobacco flavor [3], was identical in all respects with the natural compound. The substance was prepared in low yield by Diels-Alder reaction of 3-buten-2-one and 4-penten-2-ol followed by cyclization. Results of our investigations concerning the exact stereochemistry will be reported later. As the new compound is permanently and exclusively present in Norway spruce attacked by I". lineatum it is now l~ioassayed to clarify whether it serves as a primary attractant beside other chemical messengers such as 3hydroxy-3-methylbutanone [4, 5] and c~-pinene/ethanol [6].

14C and13C Isotope concentration in modern marine mussels from sedimentary habitats

Abstract: The production of artificial radiocarbon by nuclear weapon tests in the atmosphere and the subsequent dramatic increase of 14C concentration in natural environments, particularly since 1963, provide a unique opportunity to study the behavior of carbon in the exchangeable carbon reservoirs of the earth. In coastal marine sediments, the organic carbon does not only originate from the authigenic production of the year of deposition but is composed of differently aged fractions [1, 2]. The question arose whether this old component is a source of food for the higher benthic organisms, particularly mussels, living at the sediment-water interface. Young mussels of Cyprina islandica, a few years old, were collected from the muddy sediments of Kiel Bight, western Baltic Sea, at 21 m water depth. Cyprina lives nearly completely embedded in the sediment and filters the suspension at the immediate depositional interface. Shell carbonate and soft tissue were separately analyzed for 14C and stable carbon isotopes. Results are given in Table 1 along with the prebomb and modern activities of the atmosphere and of the bottom and surface water layer of Kiel Bight. Water activities have been nearly constant on average during the last few years, the difference between the two layers being related to the hydrography of Kiel Bight [3]. The radiocarbon isotope concentration of the organic fraction of the sediments is masked today by the supply of dead carbon from fossil-fuel burning [1, 2]. However, it can be extrapolated from the deeper sediments to have been at 90% STD in the prebomb era yielding an apparent ~4C age of 800 years. This a4C level is lower by about 7% STD than the corresponding water activity and thus evidences the existence of old organic matter in the modern deposits. The ~4C activities termed %STD refer to 95% of the NBS oxalic acid ~4C standard activity and are thus related to the natural ~4C level of the terrestrial biosphere in the preindustrial era. They were normalized to a stable carbon isotope ratio of ~513CvDB = -25%~ in order to correct for natural isotope fractionation effects. The results indicate that the shell carbonate is in isotopic equilibrium with the bicarbonate of the bottom-water layer where the mussel lives. The soft tissue, however, reflects the activity of the surface-water layer, where most of the planctogenic carbon supplied to the sediment was formed. The old organic compounds in the sediment do not appear to be digested by the mussel. The same findings were obtained for mussels of Scrobicularia plana which were collected from the muddy deposits, at + 1.2 m, of the tidal flats south of Nordstrand Isle near

The oxidative desintegration of sulfide crystals byThiobacillus ferrooxidans

Abstract: The autotrophic bacterium Thiobacillus ferrooxidans (Th.f) c a n acquire its energy through the oxidation of sulfur or iron(II). Twenty-five years ago Th.f was finally found to be responsible for the production of acid mine waters in sulfide-ore deposits [1]. Since then Th.f. has been grown systematically on many sulfide minerals. It has become the crucial agent for biological mining, a rapidly growing technique which is being successfully applied to extract metals from lowgrade ore and mineral tailings [2]. Recently Th.f has been grown successfully on chemically pure metal-sulfide compounds [3]. These experiments indicate that Th.f is able to desintegrate crystalline sulfides and to utilize their chemical energy while oxidizing them to the sulfates. We have cultivated Th.f. in shakerflask cultures adapting them to various synthetic sulfide compounds in 9K nutrient solution [4]. Naturally grown or synthetic crystals were then carefully selected and inoculated with Th.f The crystals were taken from the cultures after a period between several days and eight weeks. They were rinsed, dried and, after evaporation of a gold film, studied with a scanning electron microscope together with noninoculated reference crystals kept in the same solution. Clear marks of bacterial activity were found on natural leadsulfide crystals which split easily to yield very clean and even surfaces (PbS is known to be oxidized by Th.f [5]). In preliminary experiments other sulfide substrates (CuS, CdS) did not prove to be suitable, mainly because of rough surface structures, The traces of bacterial activity were evident as characteristic deepenings in otherwise even and undissolved surfaces. These deepenings do not have the appearance of typical chemical etching patterns and were completely absent on reference surfaces which were not exposed to bacterial activity. The bacteria which are approximately 1 Ixm in diameter can be seen sitting in the holes at various stages of their formation (Fig. 1). The cell surface appears to be rough. This is partially due to the fact that the bacteria were not chemically fixed and partially due to the loose fitting of the cell envelope, which is apparently characteristic for these gram-negative bacteria [6]. The following information about the bacterial oxidation of the sulfide surface was derived from scanning electron-microscope studies: (i) The deepenings start to develop at places of contact between the bacterial cell and the sulfide surface. (2) The depth and the dimensions of the depression increase with time of bacterial activity. The bacteria slowly sink deeper but a depth of approximately the dimension of the bacteria Fig. 1. Thiobacillusferrooxidans on PbS crystal surfaces. The dips they produce, show etching-type structures and uneven distribution. They are absent on surfaces treated with the same nutrient solution, but without bacteria (a)

Was ist ein elementarteilchen

Abstract: The question concerning the nature of elementary particles is discussed on the basis of the experimental facts and confronted with philosophical considerations. It is emphasized that certain ways of questioning have no meaning in the subnuclear domain, that in particular due to the relativistic structure of the dynamics it is not meaningful to talk about constituent parts of elementary particles.