This journal provides immediate access to some articles. Volume 33(12); December 1947 Biochemistry Studies on the Biochemistry of Tetrahymena: X. Quantitative Response to Essential Amino Acids PMCID: PMC1079074 Chemistry Effect of Increasing Food Protein Upon the Calcium Content of the Body PMCID: PMC1079075 Genetics The Effects of Isolates on the Frequency of a Rare Human Gene PMCID: PMC1079076 The Nature of Gene Action as Shown by Cell-Limited and Cell-Diffusible Gene Products PMCID: PMC1079077 The Influence of X-Rays and Near Infra-Red Rays on Recessive Lethals in Drosophila Melanogaster PMCID: PMC1079078 Mathematics On Infinite Complexes with Automorphisms PMCID: PMC1079079 An Oscillation Theorem for Continuous Spectra PMCID: PMC1079080 On the Composition of Quadratic Forms PMCID: PMC1079081 On the Problem of Similar Regions PMCID: PMC1079082 A Proof of Lower Semicontinuity PMCID: PMC1079083 Journal Matter Original table of contents page Administrative content — journal masthead, notices, indexes, etc. | ||