This volume is one of those published from the proceedings of the invited lectures to the First International Congress of Comparative Physiology and Biochemistry I organized at Liege (Belgium) in August 1984 under the auspices of the Section of Comparative Physiology and Biochemistry of the International Union of Biological Sciences. In a general foreword to these different volumes, it seems to me appropriate to consider briefly what may be the comparative approach. Living organisms, beyond the diversity of their morphological forms, have evolved a widespread range of basic solutions to cope with the different problems, both organismal and environmental with which they are faced. Soon after the turn of the century, some biologists realized that these solutions can be best comprehended in the frame work of a comparative approach integrating results of physiological and biochemical studies done at the organismic, cellular and molecular levels. The development of this approach amongst both physiologists and biochemists remained, however, extremely slow until recently.

Inhalt
Symposium I Behavioural Endocrinology of Mammals.- Neuroendocrine Control of Population Size in Rodents with Special Emphasis on the Mongolian Gerbil.- Social and Hormonal Determinants of Reproductive Patterns in the Prairie Vole.- Hormones and the Sexual Behaviour of Monkeys.- Mechanisms of Androgen-Activated Sexual Behaviour in Rats.- Neural Progestin Receptors: Regulation of Progesterone-Facilitated Sexual Behaviour in Female Guinea Pigs.- Strategies for Determining the Molecular Mechanisms of Oestrogen Regulation of Female Reproductive Behaviour.- Symposium II Behavioural Endocrinology of Birds.- Testosterone and Aggressive Behaviour During the Reproductive Cycle of Male Birds.- Phasic Effects of Hormones in the Avian Brain During Behavioural Development.- Role of Testosterone Metabolism in the Activation of Sexual Behaviour in Birds.- Symposium III Sexual Differentiation.- Endocrine Control of Behavioural Sexual Differentiation in the Male Ferret.- Aromatization: Is It Critical for the Differentiation of Sexually Dimorphic Behaviours?.- Prenatal Androgens in Female Rats and Adult Mounting Behaviour.- Searching for Neural Correlates of Sexual Differentiation in a Heterogeneous Tissue.- Sexual Differentiation is a Biphasic Process in Mammals and Birds.- Sex Differences in the Anterior Pituitary Gland.- Symposium IV Comparative Aspects of Amineigic Neurons.- Estimation of Biogenic Amines in Biological Tissues.- Neurotransmitters, Neuromodulators and Neurohormones.- The Distribution of Biogenic Monoamines in Invertebrates.- Amine-Sensitive Adenylate Cyclases and Their Role in Neuronal Function.- Biogenic Amines and the Regulation of Peptidergic Neurosecretory Cells.- Normal and Abnormal Animal Behaviour: Importance of Catecholamine Release by Nerve Impulses for the Maintenance of Normal Behaviour.- Symposium V Photo-Transduction in Invertebrate Visual Cells.- Phototransduction in Invertebrate Visual Cells. The Present State of Research - Exemplified and Discussed Through the Limulus Photoreceptor Cells.- Hypersensitivity in the Anterior Median Eye of a Jumping Spider.- Sensitizing Pigments and Their Significance for Vision.- Visual, Mitochondrial, and Pupillary Pigments of Fly Photoreceptor Cells.- Two-Dimensional Gel Analysis of Polypeptides in Drosophila Compound Eyes.