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REVIEWS 469 technique be devised to detect the transfer or exchange of minute quantities of DNA between homologues at meiosis? The firmest evidence of what goes on in meiosis was provided by Stern and Hotta's contribution. Their elegant biochemical studies with Lilium provide clear evidence for two important conclusions: (1) that each succeeding phase (prezygotene, zygotene, pachytene and postpachytene) has its own characteristic set of metabolic processes apparently concerned with commitment to meiosis, chromosome pairing, recombination, and chromosome segregation, respectively; and (2) that the DNA contains regions with specifically meiotic functions. At present Lilium stands alone, but it would seem to be a first priority to attempt to ascertain how far Stern and Hotta's conclusions apply generally. Lindsley and Sandier's genetic studies with meiotic mutants of Drosophila seem to be in agreement. This publication is clearly essential reading for all who are interested in any aspect of meiosis. Errors are few though it was a surprise to read (p. 201 et seq.) that yeast and Chiamydomonas are prokaryotes! Thirty excellent plates beautifully illustrate the cytological contributions—and no doubt add considerably to the price of the work. But need this have been set quite so high? H. L. K. WHITEHOUSE Botany School, University of Cambridge, Downing Street, Cambridge EVOLUTION. T. Dobzhansky, F. .1. Ayala, G. L. Stebbinc and J. W. Valentine. W. H. Freeman, San Fransisco, 1977. Pp. 572. £116O. This book follows in the tradition of the distinguished synoptic treaties on evolution by Dobzhansky, Stebbins, Mayr and Simpson, which in the modern idiom owes its origin to Julian Huxley's pioneering review, "Evolution The Modern Synthesis ", published 35 years ago. At that time Mendelian methods had uncovered sufficient of the relation between the gene and the phenotype, both at the level of the organism and of the population, to provide a coherent view of the processes of evolution. But the techniques used to study the molecular nature of hereditary materials and the chemistry of evolutionary responses are a recent introduction. It is the forte of the present volume that these exciting developments are at the centre of the synopsis. Thus, although much of the discussion on topics like, the genetic structure of populations, the origin of hereditary variation and patterns of speciation, has a very familiar ring, the supporting evidence has been so carefully up-dated, and subjected to a rigorously contemporary interpretation that readers will experience a stimulating degree of freshness throughout the presentation. The first half of the book covers the cytogenetic basis of the response of individuals and populations to evolution: the most crucial details of microevolution including those uncovered by the authors, especially Dobzhansky and Stebbins, are concisely documented in this section. The discerning student will enjoy the introductory chapter on the nature of evolution and on its status as a core, cultural concept in the life sciences; a theme that is effectively developed in later chapters. Chapter nine deals with phylogenetic relationships as revealed by analyses of the biologically important macromolecules. As befits the recent 470 REVIEWS discontinuity in research outlook which arose from the impact of these new methods, this chapter marks a suitable point of infiexion in the dissertation. The techniques for studying the units of biochemical function in evolution are documented accurately and in sufficient detail to provide a general understanding, even for a relatively non-specialist reader. DNA hybridisation, DNA phylogenies, evolutionary trends based on homologies of enzymes and of general protein patterns, on amino acid sequences, and on immunological correspondences, are all discussed unambiguously, allowing the reader the opportunity to develop an informed opinion on their validity. One is naturally thankful for the sophistication and extraordinarily fine resolution of these elegant methods, but if only to preserve a sound orientation in the advancement of science, this should not be allowed entirely to suppress the thought that the general understanding gained from these analyses is not very different from that derived from coarser routines using very highly amplified expressions, which were the basis of Darwin's methods and materials over a century ago. Although it is reasuring to get confirmation, based on amino acid sequencing of globin proteins, that man is closer to the Rhesus monkey than to the soyabean, one is tempted to recall and paraphrase Oscar Wilde's comment when he was asked for his impressions on seeing Niagara Falls, "it would be a most interesting phenomenon if it went the other way ". Likewise, itwould add pungencyand inspiration to biology, if once in awhile such refined methods as are now available in research, did upset the established order just a little bit more than they seem to have done. The last section, chapters 10-16, deals with the evolutionary record from the origin of life through the prokaryotes to the evolution of mankind, includ- ing the cultural and ethical aspects of human evolution. There is also a fascinating, albeit brief, excursion into the future of evolution, while the final chapter provides an acute introduction to some of the fundamental questions surrounding the scientific method in studies on evolution and examines the logical structure of the theory of evolution by natural selection. If F. J. Ayala, the author of this chapter, could be persuaded to elaborate the analysis beyond relevances to evolutionary theory, the crucial awareness of philosophical implications that it stimulates should be a required experience for all students of biology. This book is excellently produced and there can be little doubt that it is a very significant and highly readable contribution on the most central theme of biology. WATKIN WILLIAMS Department of Agricultural Botany, University of Reading, Reading.