This book forges a synthesis between the discipline of behavioural ecology and what is known of the social behaviour and population dynamics of cyclic populations of vertebrates, with particular discussion of the cyclic voles and lemmings. Areas of uncertainty, and those which show promise are identified, and tests of competing hypotheses are suggested. Finally, the relevance of social dynamics to population growth and decline are examined, and a hypothesis on the role of aggressiveness in expanding populations is presented.

"What is a nongenotoxic carcinogen?" This question recurred through out the Ernst Schering Research Foundation Workshop on nongeno toxic carcinogenesis, underlining the complexity of the topic. The clarity of the view that all carcinogens act by mutating DNA, origin ally advocated by Bruce Ames nearly 20 years ago, has been clouded by the increasing numbers of compounds which are not genotoxic but which nevertheless can cause cancer. There is an urgent need to in crease our understanding of these compounds so that their risks can be evaluated realistically and decisions made from a position...