This journal provides immediate access to some articles. Volume 4(3); March 1918 Astronomy Dependence of the Spectral Relation of Double Stars Upon Distance PMCID: PMC1091402 Hypothesis to Account for the Spectral Conditions of the Stars PMCID: PMC1091403 Genetics The Effect of Artificial Selection on Bristle Number in Drosophila ampelophila and its Interpretation PMCID: PMC1091397 National Research Council Meetings of the Executive Committee PMCID: PMC1091404 Physics The Resolving Powers of X-Ray Spectrometers and the Tungsten X-Ray Spectrum PMCID: PMC1091400 Note on Methods of Observing Potential Differences Induced by the Earth's Magnetic Field in an Insulated Moving Wire PMCID: PMC1091401 Zoology The Reactions of the Melanophores of Amiurus to Light and to Adrenalin PMCID: PMC1091398 Further Experiments on the Sex of Parthenogenetic Frogs PMCID: PMC1091399 Journal Matter Original table of contents page Administrative content — journal masthead, notices, indexes, etc. | ||