The Biology Data Book has been compiled to present numerical data of biology and medicine in a convenient and accessible form for reference, and to standardize accepted constants as a basis for correlation, establish common standards for statistical studies, and provide normal values for research. The biology data are organized in the form of tables, diagrams, charts, and graphs, arranged under the following headings: Genetics and Cytology, Reproduction, Development and Growth, Morphology, Nutrition and Digestion, Metabolism, Respiration and Circulation, Blood, Biological Regulators and Toxins, Biophysical and Biochemical Characteristics, Environment and Survival, Parasitism, and Materials and Methods. Seven appendices provide information concerning estimated number of species, taxonomic classification for living plants and animals, geologic distribution, atomic weights, as well as logarithms and antilogarithms. (Author).