This journal provides immediate access to some articles. Volume 16(3); March 1930 Astronomy On Some Statistical Properties of Double Stars in Space: I. A Formula for the Estimation of the Period in a Relatively Fixed System PMCID: PMC1075981 On Some Statistical Properties of Double Stars in Space: II. On the Mean Period of Double Stars in Space PMCID: PMC1075982 Chemistry The Problem of Preparing Optically Active Free Radicals PMCID: PMC1075973 Genetics Circle Formation in Datura and Oenothera PMCID: PMC1075967 Interaction between Complexes as Evidence for Segmental Interchange in Oenothera PMCID: PMC1075968 Pollen-Tube Growth of the Primary Mutant of Datura Rolled, and Its Two Secondaries PMCID: PMC1075969 Mathematics The Problems of Lagrange and Mayer Under General End Conditions PMCID: PMC1075976 Concerning Perfect Continuous Curves PMCID: PMC1075977 Combinatory Topology of Convex Regions PMCID: PMC1075978 Some Remarks on the Problem of Plateau PMCID: PMC1075979 The Problem of the Calculus of Variations in m-Space with End-Points Variable on Two Manifolds PMCID: PMC1075980 Physics Operational Calculus in Quantum Mechanics. Some Critical Comments and the Solution of Special Problems PMCID: PMC1075970 Physical Problems with Discontinuous Initial Conditions PMCID: PMC1075971 On the Possible Influence of the Mosaic Structure of Crystals on the Determination of Avogadro's Number PMCID: PMC1075972 Physiology and Pathology The Cultivation of Treponemata from the Blood of Normal Monkeys (Macacus Rhesus) and from the Blood of Monkeys Infected with Yellow Fever PMCID: PMC1075975 Zoölogy The Implantation of Additional Hypophyseal Rudiments in Urodele Embryos PMCID: PMC1075974 Journal Matter Administrative content — journal masthead, notices, indexes, etc. | ||