This volume grew out of work on Berkeley which was presented in a dissertation several years ago. Though now much revised and greatly expanded. particularly in respect of the theory of concepts, a good part of the present text rests on this earlier foundation. I therefore gladly take this opportunity to express my appreciation to my teachers both at Indiana University and at McGill, and especially to Professor Newton Stallknecht who directed my dissertation. For permission to quote from the Berkeley manuscripts in their keeping, I have first to thank the Trustees of the British Museum, and...

Reproduction and fetal development in humans and experimental animals may be adversely affected by a wide range of drugs and environmental agents. They may be toxic in the parental generation leading to impaired germ cell formation, loss of reproductive poten- tial and infertility following chronic exposure. Deviant fetal development occurs as a consequence of cellular damage at sensi- tive stages in development. Changes seen range from intrauterine mortality and structural malformation to growth retardation with physiological and behavioural defects. Concepts on the mechanism of action of...

A. N. WORDEN, D. V. PARKE AND J. MARKS THE BACKGROUND There is nothing new about the fact that chemical substances derived either from natural products or by synthetic means .. can give rise to toxicity in animals and human beings, and that they must be subjected to controls. The earliest writings speak of such toxicity and, from the times of ancient Egypt and in the Old Tes- tament, controls have existed[l]. In the Middle Ages Paracelsus (1493-1541) noted that "All things are poisons, for there is nothing without poisonous qualities. It is only the dose which makes a thing a poison", and...