Classification of plants and animals is of basic interest to biologists in all fields because correct formulation and generalization are based on sound taxonomy. This book by a world authority relates traditional taxonomic studies to recent developments in biochemical and other fields. It provides guidelines for the integration of modern and traditional methods and explains the underlying principles and philosophy of systematics. The problems of zoological, botanical, and paleontological classification are dealt with in great detail and microbial systematics briefly.Science may be defined as the rational and objective study of the external universe by human beings. Whether the study of man himself is included, as part of science will depend on how we interpret 'human beings' in this definition. If we regard humanity as in essence an assemblage of isolated individuals, then anyone of them may regard the rest as part of the external universe and thus as 'material' for scientific study; on the other hand, if, humanity is regarded as essentially one body and science as a collective rather than an individual function, we can hardly avoid maintaining in some form or other the traditional distinction between the sciences and the humanities. The problems of classifying human beings will not be considered in detail in this book, though it will appear that if the criteria developed for other animals were applied to our own case, the chimpanzee, the gorilla and perhaps the orangutan would join us in the genus Homo.This book deals with questions that are of direct relevance to the work of all biologists as well as of all specialists in taxonomy. In addition, the clarity of the author's exposition and his felicitous style make it challenging reading for all undergraduate and graduate students in the biological sciences.R.A. Crowson (1914-1999) was lecturer in Zoological Taxonomy at the University of Glasgow. His Antipodean expedition to Australia and New Zealand was made possible by the Leverhume research fellowship, and he was able to explore America when the Museum of Comparative Zoology at Harvard University appointed him to the Alexander Agassiz visiting lectureship in 1969. The 1968 Congress of Entomology in Moscow enabled him to meet many Russian scientists with whom he had corresponded for several years. His wide-ranging interests and travels allowed Dr. Crowson to bring a truly international outlook to bear upon his subject.