Topological Methods in Chemistry. By Richard E. Merrifield and Howard E. Simmons. Pp. 233. Wiley Interscience, Chichester. 1989. £25.40.

Molecules can be considered as geometrical objects. Despite this, apart from chemi- cal applications of group theory, largely restricted to symmetrical molecules, the mathematics of geometry has not been widely applied in chemistry. Merrifield and Simmons, both of the du Pont Company, aim to change this.

Much of the book is devoted to developing the mathematical machinery to analyse the combinational structures of finite spaces. The main theme which develops is that topological methods provide tools to investi- gate nonmetric aspects of chemical struc- tures. An introduction which provides a qualitative discussion of topological spaces is followed by a more formal development of the topology of finite spaces, in some seven chapters. Part II illustrates how the concepts are applied to molecular structure.

Inevitably perhaps, the examples tend to be in the realm of hydrocarbons. This is not an area which will appeal to the wider che- mistry community, but the topic will attract the mathematically inclined specialist. Such potential readers will find the book a chal- lenge. It is not an easy work but may perhaps have an impact somewhat comparable to that achieved by the introduction of distance geometry. To a restricted community of theoretical chemists this could prove to be a seminal work.

Graham Richards

Nuclear Fusion. By Keishiro Niu. Pp. 240. Cambridge University Press. 1989. £35.00, US$ 59.50.

The author, who is in the Department of Energy Sciences of the Tokyo Institute of Technology, has produced a text essentially in four parts. The first is a broad review of the aims and physics of fusion as an energy- producing process. The second and third parts deal respectively with the relevant plas- ma physics of magnetic confinement fusion and inertial confinement fusion. The final section, written by K. Sugiura, covers the fundamental technology requirements of various proposed reactor concepts for both magnetically and inertially confined systems.

Undoubtedly the strength of the text is the breadth of its coverage but arguably this does lead to some of the mathematical arguments, particuarly in sections two and three, being too condensed and, for the unfamiliar read- er, difficult to follow without recourse to the referenced texts. Overall,. however, this text has a well balanced approach and is a wel- come addition to the literature.

T. D. Beynom

Plant Canopies: Their Growth, Form and Function. Society for Experimental Biology Seminar Series 31. Edited by G. Russell, B. Marshall and P. G. Jarvis. pp. 178. Cambridge University Press, 1989. £27.50; US$ 47.50.

This book contains the nine invited papers given by international experts at a confer- ence in March 1986. The first chapter (Campbell and Norman) provides a clear introduction to canopies and discusses methods of description and measurement. There are chapters on the modular growth of plants and how this produces the diversity of canopy form (Porter); on canopies as populations of leaves (Harper); and on diur- nal leaf movements and their effects on canopy productivity (Ehleringer and Forseth). Russell, Jarvis, and Monteith de- scribe the method of growth analysis using intercepted radiation and review the results of many studies. Van Keulen, Goudriaan, and Seligman discuss the modelling of the nitrogen economy of plants but with only passing reference to canopies. Two chapters (Raupach: turbulent transfer in canopies; McNaughton: regional interactions, in the convective boundary layer) cover microcli- matological aspects. The book ends (Nor- man) with the synthesis of canopy processes in a plant-environment model which inte- grates small-scale sub-models to the canopy and seasonal scale.

Researchers in hydrology, plant morphol- ogy, demography, and especially physiolo- gical ecology (pure, and applied to agricul- ture and forestry) will find something of interest in this book. It is not an integrated textbook but many of the chapters are thorough and stimulating reviews.

P. L. Mitchell

Natural Toxins: Characterization, Pharmacology and Therapeutics. Proceedings of Congress, Stillwater, OK, August 1988. Edited by Charlotte L. Ownby and George V. Odell. Pergamon Press, Oxford. 1989. £32.50; US$ 60.00.

This book is a formal record of plenary lectures presented in 1988 at the 9th World Congress of the International Society of Tox- inology. By using camera-ready reproduction of contributed chapters it has been possible to produce this volume within a year of the conference. One might fairly criticise its un- even style and appearance, which is often the hallmark of such productions, but this pub- lication does provide readers with up-to-date information on toxinology research. How- ever, the price for this book of only 211 pages is on the high side, especially since over 30 pages are generously allocated to subject and taxonomic indexes. Most of the chapters are brief reviews and include accounts of toxins ranging from those produced by blue-green algae to those found in venoms of snakes. Topics covered include the interaction of toxins with ion channels, cloning of toxins, three-dimensional structures of toxins, and clinical aspects of therapies. Most of the chapters are well-written and informative and will provide the expert and beginner alike with useful background reading. Tox- inology is an important field of contemporary scientific research and the contents of this book demonstrate just how rapidly this sub- ject is advancing on many fronts, particularly

following the introduction of molecular biological and computer graphics techniques.

P. N. R. Usherwood

A Cognitive Theory of Consciousness. By Bernard Baars. Pp. 424. Cambridge University Press. 1989. £27.50; US$ 44.50.

As Baars points out, 'Psychologists have neither addressed nor evaded consciousness successfully, and two major metatheories, introspectionism and behaviorism have come to grief on this dilemma'. He advocates a third approach, the functionalism of Cogni- tive Psychology - on the grounds that if consciousness is of any scientific interest at all it must play a major functional role in the human cental nervous system. To define this role Baars adopts the strategy of specifying what is different about conscious and uncon- scious processing in a wide range of psycho- logical functions, including attention, goal setting, voluntary control, monitoring ac- tion, and developing a concept of self. He integrates these differences into a model in which consciousness plays the part of a 'glob- al workspace', access to which enables in- formation to be broadcast throughout the central nervous system, and he suggests no less than 18 different, adaptive functions for consciousness.

Baars writes well and integrates a large body of experimental findings in a relatively simple fashion. The more fundamental ques- tions surrounding the mind/body problem and the nature of consciousness are ignored and it remains to be seen whether his model will stand the test of time. Nevertheless, the book makes a useful contribution to the current re-emergence of consciousness as a major area of scientific investigation.

Max Velmans

The Ocean Basins: Their Structure and Evolution. Prepared by Open University course team. Pp. 171. Pergamon Press, Oxford. 1988. Hardback £15.95, US$ 28.50; paperback £9.95, US$17.95.

Overall, as an introductory text this book is excellent - well written, concise, pretty com- prehensive, logically structured, and beauti- fully illustrated. It is extremely up to date and covers many exciting recent discoveries (e.g. black smokers). It will be an almost essential purchase for all students of oceanography and for geologists and geo- physicists alike; almost certainly, postgradu- ate students and even professionals will also find something of interest in it. The emphasis is very much on the more physical aspects of the oceans as basins with the geophysical framework, techniques, seafloor spreading, petrology, and hydrothermal processes being particularly well handled. All but the cursory reader will want to look elsewhere for more information on, for example sedimentation and the chemical aspects of ocean processes. This is, however only to be expected with a book of this relatively short length. The summary and questions sections at the end of

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