In recent years, parasitologists have learned much about the way in which parasite biochemistry differs from that of free-living organisms. Inside the host, factors such as temperature, oxygen tension, carbon dioxide concentration and pH have important consequences for the biochemistry and physiology of the parasitic organism. Strong selection pressure therefore operates at all stages of a parasite's life cycle. The parasite's adaptational response to this pressure is the subject of this book.

Many multicellular animals do not require oxygen to live but respire anaerobically. Some of these have adapted to hostile environments, such as sulphide rich habitats, others live as parasites within host organisms, while others still can perhaps be said to look back on the early days of life on earth before anaerobic respiration had evolved.

Anthony Giddens is one of the most respected and influential social theorists at work today. This wide-ranging and stimulating volume, first published in 1991, provides an authoratative and penetrating critical assessment of social theory.

In an age when continued financial and other support for teaching and research in sociology cannot be taken for granted, sociologists have been surprisingly slow to provide a clear statement of the achievements of sociology in the western world since 1950. What Has Sociology Achieved? does this by assembling twelve essays specially commissioned from distinguished authors, to which the editors add an introduction setting out the issues and a concluding chapter which draws together recurrent themes.