Discriminant conditioning of foragers in the Asian honey bees Apis cerana and A.dorsata

Abstract.

• 1 Nectivore foraging environments are typically modelled as choices among non-fluctuating rewards, but in reality they often consist of intermittent daily nectar and pollen sources. Intermittent rewards create two distinct foraging problems for colonial nectivores: re-recruitment (periodically returning to intermittent rewards) and re-allocation (finding new rewards).
• 2 The role of scent in learning and remembering the locations of discontinuous nectar rewards was examined by testing re-recruitment efficiency of Apis cerana and A.dorsata to reward-correlated scents (odour discriminant self-conditioning). Experiments examined the responses of non-naive foragers to an odour correlated with prior reward, and to odours not correlated with prior rewards, by placing different scents into a colony and observing the number of bees re-recruited to a feeding station.
• 3 Re-recruitment of non-naive foragers in both species was significantly greater in response to the conditioning scent than to the experimental controls. However, species behaviour differed in one aspect; re-recruited A.cerana foragers landed on the feeding station when unscented reward was offered, whereas re-recruited A.dorsata foragers returned but would not land without conditioning scent present in the reward.

     

Kin recognition in the ant Rhytidoponera confusa II. Gestalt odour

Two models have been proposed for the transfer of genetically determined colony odour pheromones in social insects. The ‘Gestalt’ model suggests a complete transfer of pheromones amongst all nestmates whereas the ‘Individualistic’ model suggests no significant odour transfer with nestmates bearing individually distinct odours. In experiments with the ant Rhytidoponera confusa, colonies showed significantly more aggression (12% aggression) towards nestmates that had been kept in cages with non-nestmates than they did to nestmate controls (0% aggression). Colonies also showed significantly less aggression against non-nestmates that had been kept with nestmates in a separate cage (84% aggression) than they did to non-nestmate controls (100% aggression). A second experiment indicated that workers can absorb colony-specific odours from the nest materials of other colonies. However, whilst both experiments indicated a partial Gestalt component to the colony odour (ca. 28%), the Individualistic component seemed to be more important (ca. 72%).     

Effectiveness of recruitment behavior in stingless bees (Apidae,Meliponini)

Summary We examined the ability of stingless bees to recruit nest mates to a food source (i) in group foraging species laying pheromone trails from the food to the nest (Trigona recursa Smith, T. hypogea Silvestri, Scaptotrigona depilis Moure), (ii) in solitary foraging species with possible but still doubtful communication of food location inside the nest (Melipona seminigra Friese, M. favosa orbignyi Guérin), and (iii) in species with a less precise (Nannotrigona testaceicornis Lep., Tetragona clavipes Fab.) or no communication (Frieseomelitta varia Lep.). The bees were allowed to collect food (sugar solution or liver in the necrophageous species) ad libitum and the forager number to accumulate, as it would do under normal unrestrained conditions. The median number of bees collecting differed considerably among the species (1.0–1436.5). It was highest in the species employing scent trails. The time course of recruitment was characteristic for most of the species and largely independent of the number of foragers involved. The two Melipona species recruited other bees significantly faster than T. recursa, S. depilis, and N. testaceicornis during the first 10 to 30 minutes of an experiment. In species laying a scent trail to guide nestmates to a food source the first recruits appeared with a delay of several minutes followed by a quick increase in forager number. The median time required to recruit all foragers available differed among the species between 95.0 and 240.0 min. These differences can at least partly be explained by differences in the recruitment mechanisms and do not simply follow from differences in colony biomass.     

A stingless bee uses labial gland secretions for scent trail communication (<Emphasis Type="Italic">Trigona recursa</Emphasis> Smith 1863)

The pheromones used by several species of stingless bees for scent trail communication are generally assumed to be produced by the mandibular glands. Here we present strong evidence that in Trigona recursa these pheromones originate from the labial glands, which are well developed in the heads of foragers. Analysis of the behavior involved in scent marking shows that a bee extends her proboscis and rubs it over the substrate. A single scent marking event lasts for 0.59±0.21 s while the bee runs a stretch of 1.04±0.37 cm on a leaf. According to choice experiments the bees are attracted by a feeder baited with labial gland extract (84.2±6% of the bees choose this feeder) but repelled from a feeder baited with mandibular gland extract (only 27.5±13.1% of the bees choose this feeder). They do not discriminate between two clean feeders (49.6±3% of the bees at a feeder). 87±5.1% of bees already feeding leave the feeder after the application of mandibular gland extract whereas only 6.2±4.9% and 2.6±4% do so when labial gland extract or pure solvent was applied.     

Die Fähigkeit der Bienen,visuelle Reize zu generalisieren

Zusammenfassung Auf Grund von Dressurversuchen wird gefolgert, daß Bienen visuelle Reize abstrahieren und komplizierte Erkennungs-Aufgaben lösen können. Die visuellen Erscheinungsformen der Objekte werden hierbei nicht nur nach ihrer Gestalt, sondern auch nach schwierigeren Gesichtspunkten wie z.B. der Buntscheckigkeit sowie Lage des Testobjektes im Verhältnis zu anderen Objekten im Zentralnervensystem verarbeitet. Der Begriff entsteht bei der Dressur an einer Reihe von 2–3 umgestalteten Objekten oder ist auch schon nach einer Dressur an einem einzigen Objekt zu erkennen. Der Erfolg des ersten Tests ist damit zu erklären, daß die Biene vor dieser Dressur bereits eine Vorprägung des Begriffs hatte oder daß sie eine Erfahrung besaß, die zusammen mit neuer Erfahrung ausreichte, um einen echten Begriff entstehen zu lassen. Diese Vermutung wird durch die Ergebnisse von speziellen Dressurversuchen bestätigt, in denen das Verhalten der Bienen mit anfänglicher Erfahrung in neuer Situation geprüft wurde.Diese Untersuchungen sowie die Ergebnisse anderer Autoren führen zu der Folgerung, daß bei Bienen bereits von einem intelligenten Verhalten gesprochen werden darf.

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The ability of honey bees to generalize visual stimuli

Summary Behavioural studies permit the conclusion that bees can abstract visual stimuli and solve complicated recognition problems. The appearance of objects is processed in the central nervous system not only according to their shape but also according to more difficult viewpoints such as, multicoloured and checkered or position of test object relative to other objects. A succession of two or three changes in the changes in the total pattern during training, or even a single pattern is sufficient for a concept to develop. The success of a single training pattern can be explained through previous impressions or experience in combination with the new experience. This suspicion is confirmed by special training experiments in which bees with incipient experience were tested in a new situation.These investigations and the results of other authors as well lead to the conclusion, that it is permissible to speak of intelligent behaviour in bees.

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Herrn Prof. v. Frisch danke ich herzlich für die mir wertvolle Diskussion über meine Versuche, wenn wir uns auch über die Anwendbarkeit des Intelligenzbegriffes nicht einigen konnten.

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Den Herren Prof. Dr. M. Lindauer und Prof. Dr. W. Reichardt danke ich für die kritische Durchsicht des Manuskriptes, wie auch Dr. F. G. Barth und Frau Dr. Kolb für die sprachliche Redaktion.     

Collective control of nest climate parameters in bumblebee colonies

We examined two aspects of the social control of nest climate in bumblebee colonies: which parameters of nest climate bumblebees actively down-regulate by fanning and the dynamics of the colony response as colony size increased. Colonies of Bombus terrestris were exposed to an increase in carbon dioxide, temperature or relative humidity. We performed 70 temperature trials (six colonies), 58 CO₂ trials (four colonies) and four humidity trials (two colonies). An increase in CO₂ concentration and temperature elicited a fanning response whereas an increase in relative humidity did not. This is the first report of fanning in bumblebee colonies to control respiratory gases. The number of fanning bees increased with stimulus intensity. The colony response to a CO₂ concentration of 3.2% was comparable to the colony response to a temperature of 30°C. A marked fanning response occurred at 1.6% CO₂, a concentration never exceeded in a large field nest during a pilot measurement of 10 days. We investigated the colony response over a wide range of colony sizes (between 10 and 119 workers). The proportion of the total workforce invested by colonies in nest ventilation did not change significantly; thus, the number of fanning workers increased with colony size. Furthermore, as colony size increased, the dynamics of the colony response changed: colonies responded faster to perturbations of their environment when they were large (60 or more individuals) than when they were small. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Secretions of the interaural gland contain information about individuality and colony membership in the Bechstein's bat

Mammals use chemical signals for individual and kin recognition, to establish social hierarchies, mark territories and choose mates. The nocturnal and social lifestyle of bats suggests that, besides acoustic signals, they also use scent to communicate. We investigated in the communally breeding Bechstein's bat, Myotis bechsteinii, whether secretions of the facial interaural gland contain information that can be used for individual and colony recognition. Since female Bechstein's bats live in closed societies and show cooperative behaviour, we predicted they would recognize colony members. We analysed interaural gland secretions, which we repeatedly sampled from 85 females belonging to four free-ranging colonies. Gas chromatography/mass spectrometry profiles were individually specific and differed between colonies. Comparing odour profiles between colonies we found a relation between chemical similarity and the mitochondrial haplotype of colony members. Within colonies there was no correlation between mass spectrometer profile similarity and genetic relatedness. Our results suggest that female Bechstein's bats may use interaural gland secretions for individual and colony recognition but not to infer kinship directly.Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.      

Nest Entrance Marking with Colony Specific Odors by the Bumble Bee Bombus occidentalis (Hymenoptera: Apidae)

We investigated the ability of naturally foraging female bumble bees (Bombus occidentalis) to recognize their nest entrance in the field. In a blind binary-choice paradigm, females discriminated between nest entrances tipped with caps from their own nest entrances and entrances tipped with caps previously associated with foreign heterospecific or foreign conspecific colonies. Washing caps in organic solvents eliminated the manifestation of this nest-entrance recognition and significantly decreased the episodes of antennating caps. These results indicate that bees deposit colony-specific chemicals on nest entrances that are later perceived via contact chemoreception. Females treated foreign heterospecific and foreign conspecific caps similarly, suggesting that bees may not assess or respond to the degree of similarity between their own colony odor and a foreign colony odor.     

Catecholamines affect storage and retrieval of conditioned odour stimuli in honey bees

• 1.1. The effects of injected catecholamines and their analogues on odour learning in honey bees is described.
• 2.2. Dopamine blocks the retrieval of a learned odour signal with a specific time course and does not block the storage of this signal.
• 3.3. Noradrenaline blocks retrieval and storage of a conditioned odour signal.
• 4.4. Amphetamine shows the same effects as noradrenaline.
• 5.5. Haloperidol has no affect on memory retrieval or storage.

     

The pollination biology ofHibbertia stricta (Dilleniaceae)

The exines of pollen grains ofHibbertia stricta (DC.)R. Br. exF. Muell. (Sect.Pleurandra) wear an oily, yellow pollen coat that stains positively for lipids. The pollen is collected by asocial bees, exclusively. The most common floral foragers are members of the genusLasioglossum (subgenusChilalictus;Halictidae) and they harvest pollen via thoracic vibration. As these bees cling to the inflated anthers their pollen smeared bodies come in contact with either of the two wet, nonpapillate stigmas. The stigmas respond positively to cytochemical tests for the presence of esterase immediately following expansion of the corolla, indicating the effective pollination period. The foraging patterns of the bees are narrowly to broadly polylectic. AsH. stricta flowers are nectarless, it is not surprising that bees bearing mixed pollen loads always carry the pollen of at least one nectariferous, coblooming plant. The pollination biology ofH. stricta is compared with otherHibbertia spp. and with pollen flowers in general.     

Antennal responses of an oligolectic bee and its cleptoparasite to plant volatiles

Cleptoparasitic or cuckoo bees lay their eggs in nests of other bees, and the parasitic larvae feed the food that had been provided for the host larvae. Nothing is known about the specific signals used by the cuckoo bees for host nest finding, but previous studies have shown that olfactory cues originating from the host bee alone, or the host bee and the larval provision are essential. Here, I compared by using gas chromatography coupled to electroantennographic detection (GC-EAD) the antennal responses of the oligolectic oil-bee Macropis fulvipes and their cleptoparasite, Epeoloides coecutiens, to dynamic headspace scent samples of Lysimachia punctata, a pollen and oil host of Macropis. Both bee species respond to some scent compounds emitted by L. punctata, and two compounds, which were also found in scent samples collected from a Macropis nest entrance, elicited clear signals in the antennae of both species. These compounds may not only play a role for host plant detection by Macropis, but also for host nest detection by Epeoloides. I hypothesise that oligolectic bees and their cleptoparasites use the same compounds for host plant and host nest detection, respectively.Key words: Macropis fulvipes, Epeoloides coecutiens, Lysimachia punctata, oligolectic oil-bee, floral scent, dynamic headspace, GC-EAD, cuckoo bee, host nest findingBees are the most important animal pollinators worldwide, and guarantee sexual reproduction of many plant species.^1,2 This is especially true for female bees, which collect pollen and mostly nectar for their larvae and frequently visit flowers. For finding and detection of suitable flowers, bees are known to use, besides optical cues,^3,4 especially olfactory signals.^5–8 However, c. 20% of bees do not collect pollen for their larvae by their own, but enter nests of host bees and lay eggs into the broodcells.^1,9 The parasitic larvae subsequently feed the food that had been provided for the host larvae. These so called cuckoo or cleptoparasitic bees can be generalistic, indicating that they use species of several other bee groups as host, whereas others can be highly specialized, laying eggs in cells of only few host species.¹ Until now little is known about the cues used by the cuckoo bees for finding host nests. Nevertheless, Cane¹⁰ and Schindler¹¹ demonstrated that parasitic Nomada bees use primarily visual cues of the nest entrance holes for finding possible nests, and olfactory cues for detection of suitable host nests. The chemical cues used by the cleptoparasites originate from the host bee^10,11 and also pollen,¹⁰ the main larval provision. In most bee species, pollen is mixed together with nectar as larval provision, and both floral resources are known to emit volatiles.^12,13 It is unknown, whether cuckoo bees in search for host nests also use volatiles originating from nectar. While the odours of the host bee used as signal by the cleptoparasites, e.g., cuticiular hydrocarbons and glandular secretions, are often species-specific,¹⁴ the chemical cues from the larval provision may just indicate the presence of pollen in the nest without more specifity. As a consequence cuckoo bees could use species-specific host odours to detect nests of a suitable host, and odours released from the larval provision could indicate to them that broodcells are foraged. However, especially those cuckoo bees with oligolectic hosts foraging pollen only on few closely related plant species,¹ may also use the olfactory signals from host broodcell supplies as more specific cue for host nest detection. Thus the same signal from certain flowers may be used for different informations: for the host bee for host plant and for the cuckoo bee for host nest detection.In this concern I tested oligolectic Macropis (Melittidae, Melittinae) and its specific cuckoo bee, Epeoloides (Apidae, Apinae) by using gas chromatography coupled to electroantennographic detection (GC-EAD) on floral scent of Lysimachia (Myrsinaceae). Macropis is highly specialized on Lysimachia, because it is not only collecting pollen from plants of this genus, but also floral oil. Both floral products are the only provision for the larvae.^1,15 Recently, we have shown that the oil bee Macropis is strongly attracted to floral scent of its oil host Lysimachia though the compounds used for host plant finding are still unknown.⁷ Macropis is the only host of Epeoloides, and larvae of this cleptoparasite only feed on the Lysimachia pollen-oil mixture provided for the larvae of Macropis. Worldwide, there are only 2 species of this genus, one in North America and the other in Europe/Asia.^1,16,17 I hypothesized that both bee species respond to specific Lysimachia compounds, which may be used for host plant as well as host nest detection.The measurements with M. fulvipes (F.) and E. coecutiens (F.) antennae demonstrate that both bees, host as well as cuckoo bee, respond to some scent compounds emitted by inflorescences of Lysimachia punctata L. (Fig. 1), a plant being an important pollen and oil source for M. fulvipes. Macropis responded to much more Lysimachia compounds compared to the cuckoo bee, however, two compounds elicited clear signals in the antennae of both bee species: the benzenoid 1-hydroxy-1-phenyl-2-propanone, and the fatty acid derivative 2-tridecanone. Interestingly, both compounds are also emitted from the floral oil of this plant,⁷ and both compounds were also detected in scent samples collected by dynamic headspace in the entrance of a Macropis nest (Dötterl, unpublished data). Therefore, an Epeoloides female being in search for a host nest can detect volatiles emitted from the provision of the host bee at the entrance of a bee nest, and may use these specific compounds for detection of a Macropis nest provisioned with Lysimachia pollen and oil.Open in a separate windowFigure 1Coupled gas chromatographic and electroantennographic detection of a Lysimachia punctata headspace scent sample using antennae of a female oligolectic Macropis fulvipes and a female cleptoparasitic Epeoloides coecutiens bee. (1) 1-hydroxy-1-phenyl-2-propanone, (2) 2-tridecanone.Present results show that an oligolectic oil-bee as well as its cleptoparasite detects volatiles originating from the host plant of the pollen collecting bee, and that oligolectic bees as well as their cuckoo bees may use the same specific signals for host plant and host nest finding, respectively. Biotests are now needed to test this hypothesis.     

Dressur von Bienenarbeiterinnen und Drohnen auf Pheromone und andere Duftstoffe

Zusammenfassung Mit Hilfe des Rüsselreflexes gelang es, nicht nur Arbeiterinnen, sondern auch Drohnen auf Duftstoffe zu dressieren. Jeder der sechs verwendeten Duftstoffe, darunter Königinsubstanz und Sterzelduft, konnte als Dressurduft von den übrigen Düften sicher unterschieden werden.

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Conditioning of worker and drone honeybee with pheromones and other odourous substances

Summary The proboscis extension reflex was used for conditioning worker and drone bees to odours. Six odours, including queen substance and the scent to the Nassanoff gland were used as conditioning stimuli. The animals could clearly distinguish the odours from one another.

     

Interpopulation variation in pollinators and floral scent of the lady’s-slipper orchid <Emphasis Type="Italic">Cypripedium calceolus</Emphasis> L.

Floral scent is a key mediator in many plant–pollinator interactions. It is known to vary not only among plant species, but also within species among populations. However, there is a big gap in our knowledge of whether such variability is the result of divergent selective pressures exerted by a variable pollinator climate or alternative scenarios (e.g., genetic drift). Cypripedium calceolus is a Eurasian deceptive lady’s-slipper orchid pollinated by bees. It is found from near sea level to altitudes of 2500 m. We asked whether pollinator climate and floral scents vary in a concerted manner among different altitudes. Floral scents of four populations in the Limestone Alps were collected by dynamic headspace and analyzed by gas chromatography coupled to mass spectrometry (GC/MS). Flower visitors and pollinators (the subset of visitors with pollen loads) were collected and identified. Preliminary coupled gas chromatographic and electroantennographic measurements with floral scents and pollinators revealed biologically active components. More than 70 compounds were detected in the scent samples, mainly aliphatics, terpenoids, and aromatics. Although several compounds were found in all samples, and all samples were dominated by linalool and octyl acetate, scents differed among populations. Similarly, there were strong differences in flower visitor spectra among populations with most abundant flower visitors being bees and syrphid flies at low and high altitudes, respectively. Pollinator climate differed also among populations; however, independent of altitude, most pollinators were bees of Lasioglossum, Andrena, and Nomada. Only few syrphids acted as pollinators and this is the first record of flies as pollinators in C. calceolus. The electrophysiological tests showed that bees and syrphid flies sensed many of the compounds released by the flowers, among them linalool and octyl acetate. Overall, we found that both floral scent and visitor/pollinator climate differ among populations. We discuss whether interpopulation variation in scent is a result of pollinator-mediated selection.     

A Mathematical Model of Forager Loss in Honeybee Colonies Infested with <Emphasis Type="Italic">Varroa destructor</Emphasis> and the Acute Bee Paralysis Virus

We incorporate a mathematical model of Varroa destructor and the Acute Bee Paralysis Virus with an existing model for a honeybee colony, in which the bee population is divided into hive bees and forager bees based on tasks performed in the colony. The model is a system of five ordinary differential equations with dependent variables: uninfected hive bees, uninfected forager bees, infected hive bees, virus-free mites and virus-carrying mites. The interplay between forager loss and disease infestation is studied. We study the stability of the disease-free equilibrium of the bee-mite-virus model and observe that the disease cannot be fought off in the absence of varroacide treatment. However, the disease-free equilibrium can be stable if the treatment is strong enough and also if the virus-carrying mites become virus-free at a rate faster than the mite birth rate. The critical forager loss due to homing failure, above which the colony fails, is calculated using simulation experiments for disease-free, treated and untreated mite-infested, and treated virus-infested colonies. A virus-infested colony without varroacide treatment fails regardless of the forager mortality rate.     

Beitrag zur Kieselalgen-Flora der Tatragewässer

Ohne ZusammenfassungMeinen Dank am Zustandekommen der Studie möchte ich der Slowakischen Akademie der Wissenschaften abstatten, die es mir im Rahmen der 7. Arbeitstagung der Arbeitsgemeinschaft Donauforschung ermöglichte, an der Exkursion teilzunehmen. Ferner danke ich Herrn ProfessorBíly und Herrn Dr.Hanuka für die entgegenkommend gewährten Auskünfte. Herrn Dr. phil.Krenkel bin ich für seine Hilfe bei der Ausarbeitung der lateinischen Diagnosen dankbar verbunden. Danken möchte ich schließlich Herrn Prof. DDr.Keil für die verständnisvolle Förderung der Untersuchung.     

Zur Phototaxis von Mougeotia (Mesocarpus)

Summary Mosebach undertook a quantitative study of the light intensity which changes the positive phototaxis of theMougeotia chloroplast into a negative one (this intensity is the so-called, Umschlagspunkt = UP). The UP has no definite value but depends upon the pre-treatment of the plant. The UP is lowered by pre-darkening and is raised by a few hours or even less of pre-illumination.This light effect is a double one: a) the UP depends on the concentration of CO₂ in the medium, which of course is influenced by the ratio of respiration and photosynthesis, and b) in running-water experiments there still exists an influence of the pre-illumination on the UP, which must therefore be a direct light effect and which, it is suggested, is an adaptation.The CO₂-sensitivity of the UP is not an unspecific p_H effect and cannot be duplicated by citric, oxalic or hydrochloric acid. Only acetic acid has a similar effect.The cases in which the chloroplast is found to be oblique to the light beam are discussed from a new point of view.This summary is only a very short review by the editor; for further information compare the German summary by the author, page 41.

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Mit 16 Textabbildungen

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Mit einem Nachwort vonW. Haupt

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Vor seinem letzten Abschied legte mir mein Mann die Manuskripte zweier Arbeiten in die Hand mit der Bitte, wenn nötig, statt seiner für ihre Veröffentlichung zu sorgen. Die erste Arbeit (Über die Polarisierung derEquisetum-Spore durch das Licht, Planta33, 1943) war so gut wie druckfertig. Die zweite, hier vorliegende Arbeit war vonGeorg Mosebach in dieser Fassung noch nicht für die Veröffentlichung bestimmt; trotzdem ist sie nun doch in der ursprünglichen Form erschienen — abgesehen von wenigen oder unbedeutenden Änderungen, die Herr ProfessorBuder und Herr ProfessorRuhland, Leipzig, die Güte hatten vorzunehmen. Herrn Professor Dr.J. Buder und Herrn Professor Dr.W. Ruhland spreche ich auch an dieser Stelle meinen Dank aus für alle selbstlose Hilfe, die mir bei meiner Aufgabe zuteil wurde.Erna Mosebach, 1944.     

Das Inselorgan des Crossopterygiers Latimeria chalumnae J. L. B. Smith

Zusammenfassung Das Pankreas und der Fettkörper von Latimeria chalumnae, dem einzigen rezenten Crossopterygier aus der Klasse der Coelacanthes, werden in ihrer Lagebeziehung zu Magen, Darm und Milz beschrieben. Das von Millot und Anthony (1958) als Pankreas geschilderte Organ wird histologisch als Fettkörper identifiziert. Der exokrine Pankreasanteil besteht, ähnlich wie bei anderen niederen Wirbeltieren, aus einem tubulösen System exkretorischer Zellen. Das Inselorgan ist mit dem Gangsystem verbunden. Mit der Aldehydfuchsin Ponceau de Xylidine-Färbung lassen sich A- und B-Zellen, mit der Versilberung nach Hellman und Hellerström (1960) Silberzellen darstellen. Geschwollene Zellen werden als Fixationsartefakt nach Formolfixierung betrachtet. B-Zellknospen an den Gängen werden als erste phylogenetische Ansätze zu einer Dissemination des Inselorgans in das exokrine Parenchym hinein gedeutet. Zellen zwischen den exokrinen Tubuli werden beschrieben. Die Befunde werden mit den Ergebnissen am Pankreas niederer Wirbeltiere und Säuger verglichen.

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Summary The topographical anatomy of the pancreas and the fat-body of Latimeria chalumnae, the only living Crossopterygian of the suborder of Coelacanths, is described. The organ, which was considered by Millot and Anthony (1958) to be the pancreas, has been histologically identified as a fat-body. The exocrine part of the pancreas consists of a tubulous system of exocrine cells, which are similar to those of lower vertebrates. The islet-organ is connected to the ductsystem. The aldehydfuchsin Ponceau de Xylidine-staining makes it possible to demonstrate - and -cells, the argyrophil reaction according to Hellman and Hellerström (1960) silvercells. Swollen cells are thought to be fixation artefacts due to formalin-fixation. -cellbuds, which are attached to the ducts, are regarded as the first phylogenetic beginning of dissemination of the islet-organ into the exocrine tissue. Cells between the exocrine tubules are described. The findings are compared with the results of the investigations of the pancreas of lower vertebrates and mammals.

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Herrn Dr. G. v. Wahlert, Forschungsstelle für Ichthylogie in Ludwigsburg, danke ich für die freundliche Überlassung des Untersuchungsmaterials.     

Glycoconjugates in the secretory epithelium of the chicken mandibular gland

Summary In the secretory epithelium of the chicken mandibular gland, glycoconjugates have been studied by means of histochemical methods of light and electron microscopy. In light microscopy, a series of histochemical procedures have been employed which included lectin—peroxidase—diaminobenzidine methods and a digestion technique with neuraminidase or-amylase. In electron microscopy, a battery of methods were used that corresponded to those employed in light microscopy. In the secretory cells of the chicken mandibular gland, vicinal diol- and sulphate-containing glycoconjugates with sialic acid,-d-mannose,-d-glucose and-d-galactose residues were visualized and the possible histophysiological significances of such glycoconjugates were discussed with special reference to the functions of the salivary gland.     

Übersicht über die Pflanzengesellschaften des Cynosurion-Verbandes in den Karpaten

Zusammenfassung Durch die Verarbeitung eines umfangreichen, wenn auch oft unvollkommenen Materials gewinnen wir ein Bild über die Systematik der Pflanzengesellschaften des Cynosurion-Verbandes der Karpaten. Es ist dies ein erster Versuch einer Revision, Umwertung und zönotaxonomischen Eingliederung der bis zu dieser Zeit wenig bekannten und unter verschiedenen Benennungen publizierten Gesellschaften, die durch einzelne Autoren auch in andere höhere zönotaxonomische Einheiten eingereiht wurden. Durch eine Verarbeitung von über 1300 Aufnahmen im gesamten Karpatengebiet zeigte sich, daß alle beweideten oder gemähten und beweideten Gesellschaften zum Cynosurion-Verband gezählt werden können. Aus der Analyse und Synthese, aber auch durch den Vergleich mit westeuropäischen Gesellschaften geht hervor, daß es sich um mehrere Gebietsassoziationen handelt.Die Tieflandsweiden im pannonischen Bereich, also der inneren Karpatenzone, gehören zur Assoziation Trifolio-Lolietum Krippelová 67. Die Weiden der Talalluvien in mittleren und höheren Lagen der Karpaten können zur Assoziation Lolio-Cynosuretum Tx. 37 gezählt werden, sind aber von einer unterschiedlichen trockenliebenderen Art. Floristische Unterschiede zwischen den mesophilen Talweiden und den wärmeliebenden Tieflandsweiden sind in der Tabelle Nr. I angeführt. Die Fettweiden der Alluvien in den Karpaten unterscheiden sich floristisch sehr scharf von den Magerweiden auf den Abhängen. Das Bindeglied zu den Weiden auf Hängen bildet die Subassoziation Lolio-Cynosuretum alchemilletosum (Grodz. & Zarz. 65) Jurko emend., die durch trophische Standortfaktoren bedingt ist.Die Bergweiden im Karpatenbereich können auf Grund ihrer floristischen Zusammensetzung und oekologischen Bedingungen zu drei Lokalassoziationen gezählt werden. Für die Westkarpaten ist die Assoziation Anthoxantho-Agrostietum (Sill. 33) Jurko emend. typisch. In mittleren Höhen der rumänischen Karpaten ist die Assoziation Festuco-Agrostietum Csürös-Káptalan 64 verbreitet und in höheren Lagen die Assoziation Agrosti-Festucetum montanum Csürös & Resmeri 60.Die Differenzialarten dieser gegenüber dem Festuco-Cynosuretum Tx. 40 ap. Bük 42 artenarmen Gesellschaften und teilweise auch die untereinander unterschiedlichen Arten sind in der Tabelle II angeführt. Weitere Einzelheiten über ihre Differenzierung sind im Text beschrieben. Auf Grund bisheriger und zugänglicher Erkenntnisse können für die einzelnen Gesellschaften mehrere Subassoziationen festgesetzt werden, die am Schluß dieser Arbeit in einer gänzlichen Übersicht des Systems der Gesellschaften des Cynosurion-Verbandes im Karpatenbereich zusammengefaßt sind.

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Summary Evaluation of comprehensive, though often incomplete, phytocoenological material yields a picture of the system of plant communities of the alliance Cynosurion from the Carpathian region. This is the first attempted re-evaluation for coenotaxonomic ranking of plant communities from this region so far little known which have been published under different names and sometimes included in quite different higher coenotaxonomic units by some authors.By analysis of 1,300 relevés covering the whole of the Carpathians it is shown that all grazed, or cut and grazed grassland communities can be incorporated into the alliance Cynosurion. From these comparisons as well as from observations made in relation to West European communities it follows that these must be treated as regional associations different from the West European associations.The lowland pastures of the Panonian region, that is from the inner zone of the Carpathians, belong to the association Trifolio-Lolietum Krippelová 1967. The pastures of the alluvial valleys of the middle and higher Carpathians can be assigned to the association Lolio-Cynosuretum Tüxen 1937. Floristic differences between the mesophilous valley pastures and the lowland pastures are given in Table I. The fertile alluvial pastures and the more extensive pastures on the Carpathian slopes differ very much floristically. The connecting link between these two consists of the sub-association Lolio-Cynosuretum alchemilletosum (Grodz. & Zarz. 1965) emend. Jurko which is determined by site trophic factors.On the basis of their floristic composition and ecological conditions the slope and mountain pastures of the Carpathian region can be incorporated into three regional associations. In the west the typical association is Anthoxantho-Agrostietum (Sillinger 1933) emend. Jurko. In the Roumanian or middle Carpathians the principal association is Festuco-Agrostietum Csürös & Káptalan 1964 with the association Agrosti-Festucetum montanum Csürös & Resmeri 1960 at higher altitudes.Differences in the species composition of these associations from the Festuco-Cynosuretum Tüxen 1940 ap. Bük. 1942, as well as differences in species composition between the respective associations, are listed in Table II. Additional details concerning these differences are provided in the text.On the basis of the information available for the individual communities the multiple sub-associations were determined. These are mentioned in the review of the system of communities comprising the alliance Cynosurion from the Carpathian region which is included at the end of this paper.

     

Pollination of the “carrion flowers” of an African stapeliad (<Emphasis Type="Italic">Ceropegia mixta</Emphasis>: Apocynaceae): the importance of visual and scent traits for the attraction of flies

Flowers that mimic carrion or faeces exhibit unusual traits, the evolution and functional significance of which remain poorly understood. Odour is an important pollinator attractant, but visual traits and interactions between visual and scent traits have seldom been considered. We studied pollination of the “carrion flowers” of Ceropegia mixta [= Orbea variegata], analysed floral traits and used manipulative experiments to explore the contributions of visual and scent traits to pollinator attraction. Flowers were pollinated primarily by Musca domestica (Muscidae), with lesser contributions by Calliphoridae and Sarcophagidae flies. The floral odour (analysed using gas chromatography–mass spectrometry) was dominated by oligosulphides and phenol. Comparison of floral and abiotic background colours (analysed using reflectance spectrometry) using a fly colour vision model suggested that flowers would be chromatically indistinguishable from the background. Comparison of fly arrival rates at concealed (but still scented) versus exposed flowers showed that flies can locate flowers without visual cues, but visitation was higher when the flowers were visible. Experiments using model flowers with odour supplied by real flowers (to explore the significance of dark flowers and dark spots on a pale background, which both occur frequently in flowers that mimic carrion or faeces) showed that scented black flowers attracted significantly more flies than similarly scented human-yellow flowers, while the presence or size of black spots on the corolla had no effect on the attraction of flies. Our results suggest that there is a visual component to fly attraction, but some traits, such as the mottled patterning, may not have evolved to enhance pollinator attraction.