Metamorphosis and the transition from larvae or embryos to juveniles in fishes are important in order to answer, for example, questions about: (1) life-history styles and their modifications in evolutionary perspective and within current environmental demands; (2) the development and application of fisheries recruitment models, (3) the use of ontogenetic scales for interspecific comparisons, (4) the identification of ontogenetic shifts in resource use, and (5) the discovery of evolutionary interrelationships of species or genera. This volume is dedicated to recent studies and reviews of existing knowledge on this insufficiently-addressed area of ichthyology. Most of the papers in this volume were presented in Bratislava, Slovakia, at the 1st International Workshop of the Fish Ontogeny Network of Europe (FONE) in September 1997, a meeting sponsored in part by the European Commission. This volume emphasizes an integrated approach to the study of fish ontogeny, which is a process during which one event is related to another and everything is related to everything else, encompassing physiology, morphology, behaviour and niche. Within this comprehensive perspective, the papers in this volume are grouped along four major themes: reflections on early ontogeny and metamorphosis, organism-environment relationships, ontogeny of predator-prey interactions, and behaviour and ontogeny. Among other issues, the papers consider topics such as whether one can identify when fish metamorphosis ends, whether the larva period begins with hatching or with the onset of exogenous feeding, whether fish ontogeny is saltatory' or gradual', and whether larvae are eliminated in some fishes with direct development. The keynote paper of this volume reviews the main topics within contemporary paradigms and the final paper concludes that the onset of the juvenile period can be identified in some species, but precision remains problematic, emphasizing the need for further research in this dynamic area of fish biology.

The need to gather available data on the Eurasien huchen - an important salmonid species - has been forced by a plain and, unfortunately, common fact of our times: the numbers and distribution of this biggest of salmonids have begun to decline and its range has begun to shrink. A seminar on the huchen - the European form of the species Hucha hucha - held in Zilina in February 1973 as a result of a suggestion of the Section for the Conservation of Fauna of the Slovak Zoological Society, indicated very clearly the sad situation. Data on the biology of the huchen are regrettably scarce despite several recent papers (Ivaska 1951, Svetina 1962, Prawochenski and Kolder 1968) with the aim of filling this gap. Supposing that without a thorough knowledge it is practically impossible to conserve any plant or animal species, the participants of the seminar concluded that the existing knowledge on the huchen should be compiled in an exhaustive monograph. The first such outline originated in 1977 under the authorship of J. Holcik, K. Hensel and L. Skacel, and was submitted as a research report to some of the central authorities. Even during the compilation of the report it became evident, however, that there is no difference between the huchen and its relative, the taimen. Consequently, we immediately began revising our first report, which took over three years.

The need to gather available data on the Eurasien huchen - an important salmonid species - has been forced by a plain and, unfortunately, common fact of our times: the numbers and distribution of this biggest of salmonids have begun to decline and its range has begun to shrink. A seminar on the huchen - the European form of the species Hucha hucha - held in Zilina in February 1973 as a result of a suggestion of the Section for the Conservation of Fauna of the Slovak Zoological Society, indicated very clearly the sad situation. Data on the biology of the huchen are regrettably scarce despite several recent papers (Ivaska 1951, Svetina 1962, Prawochenski and Kolder 1968) with the aim of filling this gap. Supposing that without a thorough knowledge it is practically impossible to conserve any plant or animal species, the participants of the seminar concluded that the existing knowledge on the huchen should be compiled in an exhaustive monograph. The first such outline originated in 1977 under the authorship of J. Holcik, K. Hensel and L. Skacel, and was submitted as a research report to some of the central authorities. Even during the compilation of the report it became evident, however, that there is no difference between the huchen and its relative, the taimen. Consequently, we immediately began revising our first report, which took over three years.

Metamorphosis and the transition from larvae or embryos to juveniles in fishes are important in order to answer, for example, questions about: (1) life-history styles and their modifications in evolutionary perspective and within current environmental demands; (2) the development and application of fisheries recruitment models, (3) the use of ontogenetic scales for interspecific comparisons, (4) the identification of ontogenetic shifts in resource use, and (5) the discovery of evolutionary interrelationships of species or genera. This volume is dedicated to recent studies and reviews of existing knowledge on this insufficiently-addressed area of ichthyology. Most of the papers in this volume were presented in Bratislava, Slovakia, at the 1st International Workshop of the Fish Ontogeny Network of Europe (FONE) in September 1997, a meeting sponsored in part by the European Commission. This volume emphasizes an integrated approach to the study of fish ontogeny, which is a process during which one event is related to another and everything is related to everything else, encompassing physiology, morphology, behaviour and niche. Within this comprehensive perspective, the papers in this volume are grouped along four major themes: reflections on early ontogeny and metamorphosis, organism-environment relationships, ontogeny of predator-prey interactions, and behaviour and ontogeny. Among other issues, the papers consider topics such as whether one can identify when fish metamorphosis ends, whether the larva period begins with hatching or with the onset of exogenous feeding, whether fish ontogeny is `saltatory' or `gradual', and whether larvae are eliminated in some fishes with direct development. The keynote paper of this volume reviews the main topics within contemporary paradigms and the final paper concludes that the onset of the juvenile period can be identified in some species, but precision remains problematic, emphasizing the need for further research in this dynamic area of fish biology.

Die drei Vorlesungen fiber Zahlentheorie, Determinantentheorie und Algebra bildeten den Hauptbestandteil der akademischen Vortrage Leopold Kroneckers an der Berliner Universitat, und ebenso hat sich seine wissenschaftliche Lebensarbeit zum grofsen Theile in diesen drei Gebieten bewegt. Schon in seiner Antrittsrede in der Berliner Akademie der Wissen- schaften sprach er aus, wie sehr ihn gerade diejenigen. Probleme resselten, welche der Arithmetik undder Algebra gemeint!am sind, und je weiter er selbst schaffend in seiner Wissenschaft vordrang, desto deutlicher wurde ihm der enge Zusammenhang zwischen diesen beiden grorsen Disziplinen und die Notwendigkeit, sie aus den, gleichen Ge- sichtspunkten zu behandeln. So wurde auch bei jeder Wiederholung die Verbindung zwischen jenen drei V orlesungen eine engere, und zu- letzt empfand er es als innere Notwendigkeit, sie in einen Cyklus 'zu vereinigen, dem er den zusammenfassenden Namen "Dber allgemeine U Arithmetik gab. In seinen V orlesungen wollteKronecker eine Darstellung jener Disziplinen gaben, welche aUe wesentlichen gesicherten Ergebnisse der Forschung bis zur Gegenwart zu einem einheitlichen organisch geglie- derten Ganzen, zusammenfafst. So ergab sich mit N otwendigkeit eine Anordnung des Stoffes, welche in vielen Fallen von der durch die historische Entwickelung bedingten wesentlich verschieden war. Be- sonders, mufsten die Prinzipien, welche im neunzehnten Jahrhundert erst spater fur die Wissenscha. ft bestimmend hinzutraten, schon im An- fange entwickelt werden, wohin, sie ihrer Natur und Bedeutung nach gehorten, wiihrendsiesonst vielfach erst dann hinzugezogen wurden, wenn die aus' Ihnen abzuleitenden Folgerungen dargesteUt werden sollten.