X‐ray Microanalysis for Biologists . By ALICE WARLEY. (Pp. xxiii+276; illustrated; £110/$187 hardback, £39.50/$67 paperback; ISBN 1 85578 054 2.) London: Portland Press. 1997.

This is the latest volume in a series of books on techniques for electron microscopy. This series is indispensable and covers almost all techniques applicable to EM. All aspects of -ray microanalytical techniques are dealt with here. Each chapter includes a comprehensive list of references so that the reader interested in a specific aspect would have no difficulty in obtaining further information. An introductory chapter starts with a simple discussion of -ray production and relates it to biological specimens which present quite different problems to material science specimens. This chapter also includes an extensive discussion of the safety implications of all stages of -ray microanalysis. The approach to hazards is sensible and practical. Chapter 2 gives a detailed description of the physics involved in the production of -rays. This is a model of succinctness and clarity, and is followed logically by a chapter detailing the interaction of the electron beam with the specimen. In particular the discussion of ways of minimising specimen damage is thorough and useful. After this theoretical setting of the scene, Chapter 4 describes the generation and collection of -rays. This is very comprehensive and discusses the different uses of scanning and transmission electron microscopes, electron gun design, vacuum systems and specimen holders. The differences between wavelength dispersive (WDS) and energy dispersive (EDS) are extensively discussed and summarised in a clear table. Several pages are used to describe -ray detection in an EDS system followed by an equally exhaustive discussion of ways in which the signal is altered after generation. The next section describes the importance of detector performance and beam-specimen-detector geometry. Understanding this geometry is particularly useful with respect to tilting the specimen and the use of thin biological specimens. Finally the problems of backscattered electrons are discussed. Chapter 5 is a detailed account of specimen processing and methods for quantification. This begins with the theory and progresses neatly into practical applications and examples of quantification. The various problems and corrections necessary are discussed, as is the use of thin, semi-thin and thick specimens. Having read all these mainly theoretical chapters, the reader is now ready to do some experiments. The various methods of specimen preparation are described in Chapter 6. It quickly becomes clear that there is no one ideal method. The specimen can be chemically fixed, embedded and sectioned by standard techniques but routine osmium fixation or heavy metal staining can produce -rays that overlap with those being investigated. Cryofixation and sectioning are better, especially when quantification is planned, but they are more technically demanding and may also involve capital outlay. The discussion of these latter techniques is careful and detailed and includes minimising movement of elements when preparing specimens from warm-blooded animals, the effects of desiccation and cryoprotectants and the different techniques used in preparing whole tissues and cultured cells. Cryoultramicrotomy is described in detail. As always it sounds much easier in theory than producing useable sections is in practice. Freeze substitution and resin embedding are easier techniques but accompanied by the possibility of elemental translocation or even loss, although this is controversial. There is a useful table of substitution media and references. Preparation and analysis of fluids is dealt with in the same thorough way. Where appropriate, storage problems are dealt with for the various types of preparations. Having read the first chapters and understood the theoretical basis of -ray microanalysis, decided on the most appropriate technique to use and prepared the sections, the worker is now ready to analyse their specimens. Chapters 7 and 8 deal with qualitative and quantitative analyses respectively. They continue the same high standard as the rest of the book. All aspects of analysis are covered including potential problems and calibration. Producing a spectrum is relatively straightforward but quantitative analysis is somewhat more demanding. There is an invaluable section on the preparation of standards of various types. The discussion on interpreting the results and calculating the minimum detectable concentration is also very useful. Finally Chapter 9 deals with mapping techniques and their application to biological specimens. Considerable caution needs to be employed in their use and they need to be combined with spot analysis for best results. The appendices detailing sources of information and supplies round off a book that should be on the shelves of anyone using -ray analysis techniques and should be the first book consulted by those contemplating analysis for the first time.