Paläoökologische Rekonstruktion von Wirbeltieren: Möglichkeiten und Grenzen

The constraints on paleoecological analyses of fossil vertebrates are discussed using the example of Permo-Carboniferous amphibians. Paleoecological interpretations based on the study of the vertebrates as well as the fossil-bearing de-posit are generally inexact and possibly even inaccurate. Thus as many aspects as possible must be examined — the animal with all of its anatomical components and the fossil-bearing deposit with all available Information concerning sedimentology and taphonomy. Comparisons based on constructional morphology permit ecomorphological characterization of a fossil organism, with an optional band width for different ecological parameters. Individual parameters can be further re-fined through a search for evidence regarding the actual ecological band width, specifically in terms of diet and habitat. Reliable, broadly based paleoecological analyses can only be done for fossil occurrences that preserve many, more or less articulated specimens of vertebrates, and, even in those in-stances, only for more or less aquatic forms. This is particularly applicable for higher-level studies at the level of “population” or ecosystem. The study of temporally much averaged “populations” can provide data concerning age distribution for and growth-related ecological changes in a particular species. Studies of an ecosystem aim to reconstruct the structure and functions of that System through a reconstruction of the food web. On this basis, evaluation of the ecological role of the species in the context of paleocommunities is possible.     

Möglichkeiten und Grenzen einer Ökosystem-Rekonstruktion am Beispiel des spätpaläozoischen lakustrinen Paläo-Ökosystems. 1. Theoretische und methodische Grundlagen

In analogy to ecosystems, palaeoecosystems are defined here as the palaeocommunities of a given area and their relationships to the abiotic variables of their respective environments. They are characterized by (a) their species diversity, (b) the trophic structure of their palaeocommunities, based on their food webs, and (c), based on their detailed historical development, ecosystem functions such as stability, resilience, and succession. Due to numerous taphonomic biases, palaeocommunities can only be reconstructed from very few fossil horizons (taphocoenoses). Important conditions for such reconstructions are an uninterrupted vertical sequence of taphocoenoses with little time-averaging, excellent fossilization potential, a minimal percentage of allochthonous species in the taphocoenoses, and reliable evidence concerning the original trophic interactions between the species or trophic guilds of the palaeocommunities. The following topics are discussed in detail: Taphonomic assessment concerning fossilization potential; estimation of autochthonous vs. allochthonous components, and time-averaging; reconstruction of food webs and their interpretation in terms of extant food webs, such as web parameters; various ecosystem functions, especially successions and structuring processes, and the limited possibilities for their reconstruction.     

Vergleich der Funktionsmorphologie und Paläoökologie zweier Rhabdocidariden (Echinodermata: Cidaridae)

The general shape of test, spine and tubercle morphologies, and ambulacral pore characteristics ofRhabdocidaris nobilis (Münster 1826) andRhabdocidaris reginae n. sp. from the Upper Jurassic are interpreted in functional terms. Results are compared with an independent sedimentological and palaeoecological analysis of the host sediments. The morphological interpretation ofRhabdocidaris nobilis suggests a low energy, possibly partly dysaerobic, firmground setting as is evidenced by (1) the occurrence of slit-like C isopores and (2) tubercles with a broad muscle attachment area indicating strong, motile stalking spines. The morphological interpretation ofRhabdocidaris reginae suggests principally the same mode of life. However, the sedimentological and palaeoecological analysis of the host sediments suggest quite a different environment forRhabdocidaris reginae relative toRhabdocidaris nobilis. This phenomenon can be explained by the physiological characteristics of echinoids.     

Fertilität und Sexualität

Zusammenfassung Bei autopolyploiden Formen vonBryophyllum daigremontianum nimmt mit steigender Valenz die Blütenzahl je Pflanze und der Przentsatz an fertilem Pollen ab.Bei den weitgehend sterilen F₁-Pflanzen der KreuzungBryophyllum crenatum x daigremontianum fällt die Blütenzahl mit steingender Valenz. Die Pollenfertilität nimmt von n-zum 2n-Pollen erheblich zu, vom 2n-zum 4n-Pollen wieder ab, ohne den Sterilitätsgrad des n-Pollens zu erreichen.Bei verschiedenen diploiden F₂-Klonen der gleichen Kreuzung besteht offenbar keine Beziehung zwischen Blütenzahl und Pollenfertilität. Mit Verdoppelung der Chromosomenzahl steigt auch bei diesen Pflanzen die Pollenfertilität in der Regel an. Die Zunahme der Fertilität ist bei den einzelnen Klonen sehr verschieden, sie scheint im allgemeinen um so größer zu sein, je geringer die Fertilität der diploiden Pflanzen ist.Aus den Befunden und aus einer Reihe bereits früher bekannter Tatsachen wird geschlossen, daß es sich bei der Pollensterilität und bei der sich in der Blütenzahl je Pflanze manifestierenden Sexualität um voneinander unabhängige Eigenschaften. handelt.Die Bedeutung dieser Tatsache für die Polyploidiezüchtung wird erörtert.Mit 3 AbbildungenFrau Prof. Dr.Elisabeth Schiemann zum 80. Geburtstag gewidmet.     

Qualität und Resistenz

Summary The quality of wines and unfermented grape juices depends, among others, on their biotic value, checked by biological tests. This value shows a positive correlation with the degree of resistance of the plants to botanical and zoological parasites and the pathogenic effects of their products. Wines and juices of low biotic value fromVitis varieties and species with high resistance were fed to hens and chicks. Treated chicks from untreated parents and untreated chicks from treated parents developed certain anomalies, partly expressed by malformation of the legs and by cramplike conditions attributable to deficient nervous function. The relation between the changes caused in the yolk and egg white by specific biostatica in wines and grape juices fed to fowl and the indicators of grape resistance are discussed.     

Nukleinsäureketten und Genvermehrung

Ohne Zusammenfassung     

Zentrifugiernng und Protoplasma-Viskosität

Ohne Zusammenfassung     

Fossilführung und Palökologie des lagunären Massenkalkes (Devon) im Sauerland (Rheinisches Schiefergebirge)

The Massenkalk north of Brilon (East-Sauerland) and north of Balve (West-Sauerland) is of lagoonal character and is Upper Givetian (Middle Devonian) in age. Stromatoporoids, which can be subdivided into different growth forms (spherical to tabular, encrusting, thin laminar, branching), are the main reef building organisms. The species of the branching stromatoporoidAmphipora, which are hard to distinguish, dominate. The two thin laminar speciesStromatopora cygnea Stearn 1963 andStachyodes (Keega) jonelrayi Stearn 1975 are described for the first time from Western Europe. Tabulate corals represent about 20 % of the reef-builders and permit important inferences about the restriction of environment. Rugose corals and calcareous algae are rare. Reef dwelling organisms are less important; among these brachiopods, molluscs, foraminifera, calcispheres, and ostracods are, however, widespread. - Several associations of reef-builders that depend on different water depths can be distinguished. Their composition varies according to the restriction of environment. With increasing water depth water energy increased on the carbonate platform. The analysis of the stratigraphical distribution of the species of the reef-builder fauna allows no more but vague stratigraphical classifications.     

Zoologische und paläontologische Ostracoden-Systematik

Systematic rules for the OrdoOstracoda are results of two different ways of study. Palaeontologists consider for systematic purpose the shell to be of the highest importance whereas zoologists prefer to use the differences of the interior. These two different ways of consideration are of no significance for the Palaeozoic and Mesozoic species, however of greatest importance for the Cenozoic ostracoda. There are many species with “homoeomorph” shells which are stated by zoologists according to the form of their interior only. On hand of the genusCandona, the author tries to explain that “homoeomorphism” is not present if the form of the shell would be studied in a more subtile way. Negligence of the form of the shell in the zoological system is not justified. Species which differ in the form of their members have sufficiently distinct differences with regard to their shells too.It is emphasized that each of the two analytists, the palaeontological as well as the zoological one, may pay more attention to the fact that, after all, one has to deal with one and the same animal group.     

Kapillaren und perikapilläre Räume im Hypothalamus-Hypophysen-System und ihre Beziehungen zum Nervengewebe

Zusammenfassung Elektronenmikroskopische Beobachtungen an den Kapillarsystemen der Neurohypophyse des Meerschweinchens bestätigen, daß diese Gefäße eine Sonderstellung unter den Hirnkapillaren einnehmen. Ein Porenendothel zeichnet die Kapillaren des Portalplexus der Zona externa, des Hinterlappens und des Vorderlappens aus. Weite perikapilläre Räume umgeben die Kapillaren der Neurohypophyse im Gegensatz zu den übrigen Hirnkapillaren, die von einer Gliascheide dicht umschlossen sind. Die Baueigentümlichkeiten der neurohypophysären Kapillarsysteme weisen auf einen gesteigerten Austausch zwischen dem Blut und dem benachbarten inkretorisch tätigen Gewebe hin.Eine Besonderheit stellt das Vorkommen von Axonen und Axonendigungen in den perivaskulären Räumen um die Kapillaren der neurohämalen Kontaktzonen im Hinterlappen und der Zona externa dar. Die Nervenelemente unterschiedlichen Kalibers enthalten dort neben großen und kleinen Elementargranula auch synaptische Vesikel. Drei Axontypen lassen sich feststellen.Die Möglichkeit regeneratorischer Wachstumsvorgänge an neurosekretorisch tätigen Nerven wird diskutiert. Andererseits kommt der in der Neurohypophyse spezifisch differenzierten Glia (Tanyzyten, Pituizyten) auf Grund ihrer elektronenoptischen Struktur und ihrer engen Beziehung zu Nerven und Gefäßen eine besondere Bedeutung zu. Die lichtmikroskopisch bei Tieren beobachtete Zona granulosa (Hagen [1955]) zwischen Zona externa und Pars tuberalis der Adenohypophyse läßt sich in diesem Sinne deuten.

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Summary EM observations of the capillary system of the neurohypophysis of the guinea pig confirm that these vessels are unique among the capillaries of the brain. The capillaries of the portal plexus, the median eminence, the neural lobe and the pars anterior all possess a fenestrated endothelium. In contrast to the other brain capillaries, provided with a thick glial sheath, those of the neurohypophysis are surrounded by wide perivascular spaces. The structural peculiarities of the neurohypophysial capillary system point to an enhanced interchangeactivity between blood and surrounding endocrinous tissue.Especially noteworthy is the presence of axons and axon-endings in the perivascular space round the capillaries of the neurohaemal contact areas in the neural lobe and in the median eminence. These neural elements are of varying calibre and they contain synaptic vesicles in addition to large and small elementary granules. Three types of axon are observable.The possibility of regenerative growth-processes taking place on neurosecretory-active nerves is considered. On the other hand, specially differentiated glial cells (tanycytes, pituicytes) in the hypophysis are of particular significance on account of their EM structure and their close relation to nerves and blood vessels. The lightmicroscopically observed zona granulosa in animals (Hagen [1955]), observed between the median eminence and the pars tuberalis of the adenohypophysis, could be explainable on this basis.