This volume is an English translation of Overton's monograph on structure-activity relationships regarding anaesthetic action and toxicity. This book has been cited widely by scientists studying the correlation of biological activity with partition coefficients and the mechanism of anaesthesia. Although the original monograph was published in 1901, it should still be of value to modern toxicologists, particularly those involved in the development of quantitative structure-toxicity relationships and the predictive limitations of such models. Introductory chapters by Lipnick, Miller and Winter emphasize the importance of this text."