Survey of Biological Progress, Volume III explores the principles common to all biological areas that undergo major developments and modifications, including the embryo, botany, chromosome, insect behavior, hormones, and respiration. This volume is composed of six chapters, and begins with a presentation of the embryological concepts and the cellular components of the embryo. The next chapter deals with the trends in systematic botany of the vascular plants. Some of these trends apply equally well to nonvascular plants, as demonstrated by an upsurge of cytotaxonomic studies in the bryophytes, and the use of new techniques of importance to the systematist in such groups as the bacteria. These topics are followed by discussion on the cytologically detectable difference between the chromosome sets of related species, whether involving a difference in chromosome number or merely a change in the relative sequence of parts within a chromosome, as a cytotaxonomic difference. The remaining chapters describe the host-parasite interactions, the behavior of chemical trail-following and orientation to airborne odors of insects, the mechanism of action of hormones on cells, and the regulation of respiration rate. This book will be of value to undergraduate biology students.