This journal provides immediate access to some articles. Volume 26(9); September 15, 1940 Astronomy A Note on the Variation of Delta Scuti PMCID: PMC1078225 Galactic and Extragalactic Studies: VIII. A New Determination of the Period-Luminosity Curve PMCID: PMC1078226 The Spectrum of BD +30°3639 PMCID: PMC1078227 Galactic and Extragalactic Studies: IX. A Photometric Survey of 22,000 Galaxies in the Zone from δ = +41° to δ = +46° PMCID: PMC1078228 Botany Synthesis of Thiamin by Excised Roots of Maize PMCID: PMC1078235 Chemistry Inhibition of Carboxylase by Thiazole Pyrophosphate PMCID: PMC1078229 Genetics THE EFFECT OF FAST NEUTRONS ON THE CHROMOSOMES OF TRADESCANTIA PMCID: PMC1078232 CHROMOSOME HOMOLOGIES IN TWO SUB-SPECIES OF DROSOPHILA VIRILIS PMCID: PMC1078233 LINKAGE STUDIES OF THE RAT (RATTUS NORVEGICUS): III PMCID: PMC1078234 Mathematics On Homotopy Groups PMCID: PMC1078230 Physics On a General Rule Concerning the Half-Value Periods of Electron-Emitting Nuclei PMCID: PMC1078231 | ||