Preferring the fittest mates: an analytically tractable model.

We develop an analytically tractable model of female preference for fit mates. Our population-genetic model allows to trace the dynamics at both the individual and the population level. The preference for fit mates links ecological adaptation and mating success is individually advantageous and causes polymorphic subpopulations. This polymorphism is a strong and stable clustering in genotype and phenotype space. The alleles coding for the mating preference spread rapidly through the population, thereby increasing the selection pressure between different habitats. The resulting polymorphism exceeds the expected selection-migration equilibrium by several orders of magnitude. The evolution of preference for fit mates can, thus, act as the trigger for parapatric speciation because it initiates prezygotic isolation and divergence.

The conceptual framework of evolutionary morphology in the studies of Ernst Haeckel and Fritz Müller.

In his Gastraea studies Ernst Haeckel characterized the initial stages of the animal embryo, describing complete and incomplete cleavages in various groups, until the gastrula stage. Thereby, he was able to point out various degrees of developmental diversification in these initial stages of development. As the functional meaning of such cleavages was not clear however, it was difficult to argue about putative functional adaptations. Information about the consequences for tissue formation initiated in this primary phase of development was simply lacking. Haeckel could only provide a vague picture of a highly diversified but systematically inconsistent distribution of various types of early embryogenesis. Thereby he discusses phylogenetically preserved (palingenetic) stages of development and adaptations to certain specific situations of the embryo (cenogenesis). To decide whether such types, in the initial stages of embryogenesis, are ceno- or phaenogenetic is quite difficult. Reference to the highly diversified distribution of certain types within specific groups is an indication that there is no strict adaptive pressure on these early parts of embryonic development. This makes it possible to formulate - as Haeckel did it - the idea, that in these initial phases palingenetic attributes are dominant. Thus, he tried to use these early phases of development for the classification of larger systematic units. The result is a concept of an evolutionary morphology, that was, however, never elaborated in detail by Haeckel. Therefore, it remained without effect for evolutionary biology. On the contrary, following the Darwinian approach towards a comparative analysis of embryogenesis, Fritz Müller presented a series of examples for a comparative developmental biology that allowed one to interpret certain morphological characteristics as the outcome of common evolutionary histories within different species. For various crustacean species, he was able to demonstrate that certain attributes are not to be characterized as functionally relevant adaptations, but are evolutionarily inherited.

On the gestalt concept.

We define a gestalt as the invariants of a collection of patterns that can mutually be transformed into each other through a class of transformations encoded by, or conversely, determining that gestalt. The class of these transformations needs to satisfy structural regularities like the ones of the mathematical structure of a group. This makes an analysis of a gestalt possible in terms of relations between its representing patterns. While the gestalt concept has its origins in cognitive psychology, it has also important implications for morphology.

[Globalization and its historical location. Some remarks with the example of Ernst Haeckel]. / Globalisierung in ihrer historischen Verortung. Einige Anmerkungen am Beispiel Ernst Haeckels.

Globalization, regarded here as the extensive and profound transformation process of modernity, manifests itself to us in the way it impacts the here and now. However, it also has a prehistory with regard to both its anthropogenic effects on nature and intellectual controversies. This prehistory is important for understanding how we deal with this phenomenon. Due to the important roles science plays in the process of globalization and the, in no way insignificant, repercussions it has on the sciences themselves, this article aims to present in detail a prehistory that pointedly illustrates how we perceive our modernity, also with regard to its discrepancies which result from the various underlying conditions. In its attempt to analyze the question of contemporary perception in an exemplary way, the article below looks back at the intellectual situation prevailing around 1900. It aims to clarify lines of influence and controversial issues connected with Ernst Haeckel, particularly in terms of the mutual interconnectedness and influence of intra-academic changes and cultural reflections.

["Could not therefore the earth globe also be a large tourmaline?" A crystal, Lichtenberg and the polarity discussion before 1800]. / "Könnte nicht also auch die Erdkugel ein grosser Turmalin sein?" Ein Kristall, Lichtenberg und die Polaritätsdiskussion vor 1800.

This paper focuses on the debate on one particular phenomenon of the research into electrical charge distribution prior to 1800: the description and interpretation of polarities observed on the tourmaline. We show that in the second half of the eighteenth century this crystal became a model to distinguish and categorize different qualities of charges (electric and magnetic fluids). It will become clear that the polarity detected on the tourmaline became a key concept for eighteenth century natural philosophy, which relied on analogizing operations. We illustrate this concentrating on Lichtenbergs first lecture at the Göttingen academy of science in 1778. Thus the concept of polarity is already a central ordering category before the beginnings of the speculative enterprise of idealistic Naturphilosophy. Consequently, the physicist Johann Wilhelm Ritter, who can be positioned in that context, consciously adheres to the experimental research tradition of polarities portrayed in this paper.

'Further Development' of Mendel's legacy? Erich von Tschermak-Seysenegg in the context of Mendelian-biometry controversy, 1901-1906.

The contribution of Erich von Tschermak-Seysenegg (1871-1962) to the beginning of classical genetics is a matter of dispute. The aim of this study is to analyse, based on newly accessible archive materials, the relevance of his positions and theoretical views in a debate between advocates of early Mendelian explanation of heredity and proponents of biometry, which took place in England around 1901-1906. We challenge not only his role of an 'external consultant', which at the time de facto confirmed his status of 'rediscoverer' of Mendel's work but also analyse his ambivalent positions which are to be seen as a part of 'further development' (Weiterführung), a development of Mendel's legacy as he understood it. Second, there is an interesting aspect of establishing connections within an 'experimental culture' along the Mendel's lines of thought that was parallel to the first step of institutionalizing the new discipline of Genetics after 1905/06. Part of the study is also the analysis of contribution of his older brother Armin von Tschermak-Seysenegg (1870-1952) who--much like in the case of 'rediscovery' of 1900-1901--was for his younger brother an important source of theoretical knowledge. In this particular case, it regarded Bateson's 'Defence' of Mendel from 1902.

[Skyblue - the cyanometer of Horace-Bénédict de Saussure (1740 - 1799)]. / Himmelblau - das Cyanometer des Horace-Bénédict de Saussure (1740-1799).

The cyanometer is a simply constructed measuring instrument that enables a determination of skyblue. It consists of a color-scale that is arranged circularly going in equal steps from white to blue (Prussian blue) and finally into black. According to its inventor--Horace-Bénédict de Saussure--the azure is determined by the amount of so called opaque vapors in the atmosphere associated with meteorological phenomena. As outlined by De Saussure, the blackness of the universe seen through an illuminated and blurred medium results in azure. Thereby his instrument offers a relative scale that is consistent with color theories of his time like those of Johann Wolfgang von Goethe. The description allows the construction of the scale without the employment of standardized color-prints. Instead he provides a clear report of the necessary procedures to produce such a scale. The accuracy of this description is tested and discussed employing the methods of experimental history of science. The reception of the cyanometer in the time about 1800 and its implications on color theories is discussed.

Neurosemantics, neurons and system theory.

Following the concept of internal representations, signal processing in a neuronal system has to be evaluated exclusively based on internal system characteristics. Thus, this approach omits the external observer as a control function for sensory integration. Instead, the configuration of the system and its computational performance are the effects of endogenous factors. Such self-referential operation is due to a strictly local computation in a network and, thereby, computations follow a set of rules that constitute the emergent behaviour of the system. These rules can be shown to correspond to a "logic" that is intrinsic to the system, an idea which provides the basis for neurosemantics.

Anton Dohrn and the problems of 19th century phylogenetic morphology.

According to Anton Dohrn, evolutionary development was performed in a single progressive lineage where some proto-annelid initiated an evolutionary development that went straight on via annelids and lower vertebrates to man. From that line, a kind of metamorphosing nature, certain branches were derived, like protists or worms or even tunicates, which Dohrn thought off as degenerating groups. With that concept Dohrn came close to typological ideas of his time. Nevertheless, recent evo-devo literature seems to be influenced by Dohrn's outline of evolution.

Evolution and development: past, present, and future.

The paper tries to set right certain ideas about the history of evolutionary developmental biology. The main point is, that we had to enface the dominance of a comparative approach towards evolutionary developmental biology before 1900, which even later on was effective in Russia, for example, till the 1930s. The problem of the experimentalist approach set against this tradition was and is that there is no concept of gestalt that may allow to integrate the former comparative views and the modern mechanistic interpretations. We argue, that it would be wrong just to describe the comparative tradition as being outdated, as it may allow to get the framework for a dynamical concept of Gestalt that may integrate the ideas of morphogenesis and pattern formation worked out in evo-devo recently.

[Silhouettes: electron microscopic photography in bioscience]. / Schattenbilder: zur elektronenmikroskopischen photographie in den biowissenschaften.

The paper describes the first attempts of biological electron microphotography. It starts with a description of the early use of electron microscopy in biology, showing that electron microscopy was used as an extension of former light microscopical studies. Thus, the pictures produced by electron microscopy are interpreted as describing the micro-texture of those structures already seen in light microscopy. That was done irrespective from the specific problems of tissue preparation for electron microscopy. The use of photography in electron microscopy is discussed in more detail. It is shown that in electron microscopy, not the preparation itself which is usually destroyed or damaged during observation in the electron microscope. Thus, biological electron microscopy can be described as a real image science.

Representation of the microcosm: the claim for objectivity in 19th century scientific microphotography.

Microphotography was one of the earliest applications of photography in science. The first monograph on tissue organization illustrated with microphotographs was published in 1845. In the 1860s, a large number of introductions to scientific microphotography was published by anatomists. They argued that microphotography was a means of documenting the results of microscopic analysis, uncontaminated by subjectivity of the observer. In the early decades of the 19th century, before the general acceptance of cell theory, such a technique was of special importance, so no criteria were available to distinguish between important and superficial characters in the description of tissue microstructures. Microphotography was praised as the method of choice for documenting the scientific observations of microscopic material. Some of the microphotographic practices described in these early manuals, however, did not conform with the idea of a purely mechanical process of documentation. The authors of these manuals saw photography not as a technique which produced artifacts, but as a complete and reliable substitute for the original preparations. Thus, according to these authors, the artificial world of photography was seen as the actual representation of the microworld. Consequently, they tried to understand the microcosm by analyzing photographs instead of the microscopic preparation themselves. Such attitudes discredited the use of microphotography in the sciences. Consequently, the definitive breakthrough of scientific microphotography was delayed until the 1880s and was largely due to the efforts of Robert Koch, who made microphotography a central tool of bacteriology.

[Schelling and experiential science]. / Schelling und die Erfahrungswissenschaft.

Schelling's philosophy of nature is shown to be part of the scientific discussions of his day, not set apart from it. His terminology describing the potentialities and polarities of nature was formed during Schelling's collaboration with the physicist Johann Wilhelm Ritter. This scientist adopted the schema Schelling had developed for the categorization of natural phenomena to describe the peculiar facts that interested him in his area of research. Thus Ritter was able to develop a classification of the various phenomena of animal galvanism. Thus it can be shown that the idealistic "Naturphilosophie" was part of the scientific culture of about 1800. It is to be interpreted as philosophy of science and has to be evaluated not only in a philosophically systematic way but in particular in its influence on the way scientific categories were ordered at the time. Thereby it can be shown that the idealistic vocabulary had close correspondence to French morphology and English Natural Theology.

Constancy of ascending projections in the metamorphosing brain of the meal-beetle Tenebrio molitor L. (Insecta: Coleoptera).

The fate of ascending projections of thoracic interneurons in the metamorphosing brain of Tenebrio molitor is described. Persistent brain neurons were identified and their fate is described during metamorphosis. The projection sites of ascending elements are invariable throughout metamorphosis both in quantitative and in qualitative terms. Some of these ascending neurons are serotonin-immunoreactive and this set of neurons maintains a constant projection site within the metamorphosing brain. The alterations in the projection sites of these and other ascending neurons in the ventral nerve cord were analysed experimentally. The central projection sites of these persistent ascending neurons are not important for the maintenance of their nerve cord projections throughout metamorphosis. Experimental deletion of ascending neurons which project into the suboesophageal ganglion varies the shape of persistent central neurons.

The fate of persisting thoracic neurons during metamorphosis of the meal beetle Tenebrio molitor (Insecta: Coleoptera).

A set of motor neurons and interneurons in the thoracic nervous system of the meal beetle Tenebrio molitor L. is described that persist during metamorphosis. The motor neurons under discussion innervate the thoracic ventral longitudinal muscles and were identified by retrograde transport of intramuscularly injected horseradish peroxidase. Persisting motor neurons exhibit a complex repetitive pattern that changes only slightly during development. Additionally, the characterization of serotonin-immunoreactive neurons defines a complex set of interneurons that also persist throughout development. The fate of these identified neurons is outlined in detail with special reference to variations in their dendritic arborizations. All motor and interneurons are affected by a similar change in their shape during development. The larval neurons lack the contralateral arborization that is found in the adult beetle and is already distinguishable in the prepupa. Essentially only quantitative changes of the neuronal shape were observed during the pupal instar. No pupa-specific degeneration of certain axo-dendritic structures of these neurons was found. Removal of descending interneurons by sectioning the promesothoracic connectives causes specific degeneration of the dendritic tree of an identified serotonin-immunoreactive interneuron.

Absence of sensory input does not affect persistent neurons in Tenebrio molitor metamorphosis (Insecta: Coleoptera).

The ventral nerve cord of holometabolous insects is reorganized during metamorphosis. Certain elements, however, persist from the larval to the adult stage. A group of dorsal unpaired median neurons and a set of thoracic serotonin-immunoreactive interneurons are shown to be persistent elements in the ventral nerve cord of Tenebrio molitor. These persistent neurons retain their "bauplan" even after deprivation of the sensory neurons projecting onto them. These persistent neurons might provide a network into which newly developing sensory neurons fit during reorganization of the nervous tissue.

[Reception of research in the natural sciences in middle Germany at the Padua University betwee 1770 and 1820]. / Zur Rezeption der Naturforschung des mitteldeutschen Raumes an der Universität Padua zwischen 1770 und 1820.

The German literature on natural sciences that was present in the public libraries in Padua between 1770 and 1820 is described. The citations of German authors in the publications of Paduan naturalists of that time and of the textbooks used in Padua University are outlined. German journals on natural sciences available in Venice and Padua and Italian translations of German monographs of that time are also documented. With the foundation of the Italian Empire by Napoleon, the organization of lectures and research in the University of Padua changed drastically. In consequence, the reception of chemistry and physics was exclusively directed to France. In the descriptive natural sciences the earlier German traditions prevailed. Therein, however, Paduan sciences adopted the earlier descriptive traditions that already existed at the end of the 18th century and did not respond to the new developments in German functional morphology and physiology. Jenensian naturalists, botanists and physicists who received attention in Padua around 1800 are described as part of the empiric tradition of Central Germany and not as followers of the speculative "Naturphilosophie". There is no explicit reference to romantic sciences.