This journal provides immediate access to some articles. Volume 25(6); June 1939 Chemistry The Constitution of Secretin PMCID: PMC1077765 Genetics Mammary Tumor Development in Mice Ovariectomized at Birth PMCID: PMC1077768 Observations on the Mechanism of Induced Chromosome Rearrangements in Sciara PMCID: PMC1077769 Geology and Paleontology Eocene Amynodonts from Southern California PMCID: PMC1077766 Mathematics Class Field Theory of Solvable Algebraic Number Fields PMCID: PMC1077771 On the Representation of Groups of Finite Order PMCID: PMC1077772 Ordered Sets, Complexes and the Problem of Compactification PMCID: PMC1077773 Physiology and Biochemistry The Active Uptake of Ions into Cells and Organisms PMCID: PMC1077767 Zoölogy and Anatomy Evidence for the Existence of an Electro-Dynamic Field in Living Organisms PMCID: PMC1077770 Journal Matter Administrative content — journal masthead, notices, indexes, etc. | ||