This journal provides immediate access to some articles. Volume 33(4); April 1947 Astronomy On the Distribution of Titanium Oxide and Carbon Stars in Our Part of the Milky Way PMCID: PMC1078992 Genetics Hybridization Between Rana Pipiens From Vermont and Eastern Mexico PMCID: PMC1078994 Mathematics A Uniqueness Theorem for Eigenfunction Expansions PMCID: PMC1078995 On the Characteristic Classes of Riemannian Manifolds PMCID: PMC1078996 On the Functional Equation PMCID: PMC1078997 Pathology The Spread of Measles in the Family PMCID: PMC1078993 Journal Matter Original table of contents page Administrative content — journal masthead, notices, indexes, etc. | ||