PREFACEThis book is not a translation of Hennig's Grundziige einer Thecrie der phylogenetischen Systematik ( 1950). That work has been extensively revised by the author and much of it has been completely rewritten. The latter is the manuscript that has been translated. Consequently the text appears here for the first time; it has not been published in German. My own involvement in this project was the result of my ability to master the language, but it was my close friend and colleague, the late Dr. D. Dwight Davis, who had assumed the responsibility for translating the work. Following completion of the rough translation, Davis spent a great deal of time editing the text, but unhappily could not finish the task. The responsibility for the final form of the translation now rests with me. The translation of a work such as this poses a great many linguistic difficulties in the sense that for some German concepts there simply are no English equivalents. One of the worst examples of this is the concept of Gesetzmiissigkeit, widely used in the German technical literature. We have used the literal "conformity to law," fully realizing that there is no perfect congruence between these concepts. For example, a Gesetzmassigkeit may be no more than the repetitive occurrence of a specific phenomenon.RAINER ZANGERL

2020-08-16