ADVANCES IN COMPARATIVE AND ENVIRONMENTAL PHYSIOLOGY helps biologists, physiologists, and biochemists keep track of the extensive literature in thefield. Providing comprehensive, integrated reviews and sound, critical, and provocative summaries, this series is a must for all active researchers in environmental and comparative physiology. The present volume contains six reviews on: - Motile Activities of Fish Chromatophores. - Epithelial Transport of Heavy Metals. - Heavy Metal Cytotoxicity in Marine Organisms. - Comparative Pulmonary Morphology and Morphometry. - Molecular Adaptations in Resistance to Penicillins. - Molecular Adaptations of Enzymes From Thermophilic and Psychrophilic Organisms.