The Technique of Theory Construction

OSMOTIC REGULATION IN AQUATIC ANIMALS. By August Krogh. Cambridge: At the University Press; New York: The Macmillan Company. 1939, pp. vii + 242, $4.00. To the series of Cambridge Comparative Physiology monographs, Professor Krogh has added a treatise on "the relations between concentrations of solutions, inside and outside cells and organisms." As Professor Krogh points out, there are wide divergencies among aquatic animals. Single cells, though in osmotic equilibrium with their environment, maintain internal ionic concentrations quite dissimilar to the environment. Fresh-water fishes, in addition, maintain osmotic imbalance. His main object is "to describe the osmotic and ionic steady states in animals, to locate the mechanisms by which they are maintained, and to describe, as far as possible, their mode of working." Because of the fragmentary nature of the knowledge, and because of the diversity of the osmotic problems encountered, Professor Krogh confesses that it is exceedingly difficult to arrange the material according to physiological viewpoints and has preferred to discuss the material mainly in a purely descriptive fashion according to the major systematic groups of the animal kingdom. Therefore, his chapters are on Protozoa, Coelenterata, etc., to Reptilia, Aves, and Mammalia. In addition, there is a short chapter on Osmotic Conditions in Eggs and Embryos, another on Comments, Conclusions, and Suggestions and, finally, one on Notes on Methods. Possibly Professor Krogh's viewpoint is best exemplified by the following excerpt. He states that "Possible mechanisms for the ion transport have been proposed in special cases and models constructed, but I do not think the time is at all ripe for this final step, and I submit that the most specialized mechanisms should be studied preferentially, because they are most likely to furnish clues." The book, therefore, contains much descriptive material, but the present reviewer greatly misses the fuller description of the basic physico-chemical ideas and physiological viewpoints which would serve to enrich the treatment considerably. Perhaps another book would be needed for that. LESLIE F. NIMS.