This journal provides immediate access to some articles. Volume 24(7); July 1938 Astronomy A Metagalactic Density Gradient PMCID: PMC1077094 Genetics The Distribution of Gene Frequencies Under Irreversible Mutation PMCID: PMC1077089 Mathematics Largest Degree of a Substitution in the Groups of a Given Degree PMCID: PMC1077096 Remarks on Riemann's Doctoral Dissertation PMCID: PMC1077097 Paleontology A Tarsiid Primate and a Mixodectid from the Poway Eocene, California PMCID: PMC1077095 Physics The Mechanism of Hearing as Revealed Through Experiment on the Masking Effect of Thermal Noise PMCID: PMC1077091 The Dimensionless Constants of Physics PMCID: PMC1077092 Physiology Auxin in Isolated Roots Growing in Vitro PMCID: PMC1077090 Psychology On the Relative Contributions of Nature and Nurture to Average Group Differences in Intelligence PMCID: PMC1077093 Journal Matter Original table of contents page Administrative content — journal masthead, notices, indexes, etc. | ||