This journal provides immediate access to some articles. Volume 27(1); January 15, 1941 Botany The Twelfth Primary Trisomic Type in Nicotiana Sylvestris PMCID: PMC1078264 Chemistry Purine and Pyrimidine as Growth Substances for Lactic Acid Bacteria PMCID: PMC1078262 Genetics The Time Interval between X-Radiation of Sperm of Drosophila and Chromosome Recombination PMCID: PMC1078266 Mechanism of the Origin of X-Ray Induced Notch Deficiencies in Drosophila Melanogaster PMCID: PMC1078267 Another Case of Unequal Crossing-Over in Drosophila Melanogaster PMCID: PMC1078268 Position of Adult Testes in Drosophila Melanogaster Meigen PMCID: PMC1078269 An Analysis of X-Ray Induced Single Breaks in Neuroblast Chromosomes of the Grasshopper (Chortophaga Viridifasciata) PMCID: PMC1078270 Discovery of a Predicted Gene Arrangement in Drosophila Azteca PMCID: PMC1078271 Mathematics Critical Points and Unstable Minimal Surfaces PMCID: PMC1078272 A Note on Conformal Geometry PMCID: PMC1078273 Homotopy Relations in Fibre Spaces PMCID: PMC1078274 Note on Linear Difference and Differential Equations PMCID: PMC1078275 Maximal Subgroups of a Given Group PMCID: PMC1078276 A Unified Theory of Integration PMCID: PMC1078277 On Improperly Irregular Cyclotomic Fields PMCID: PMC1078278 A General Theory of Spectra: II PMCID: PMC1078279 General Invariants of Irregular Analytic Elements PMCID: PMC1078280 Pathology and Bacteriology Contact and Measles PMCID: PMC1078263 Zoölogy and Anatomy Isolating Mechanisms in Tree Frogs PMCID: PMC1078265 Journal Matter Original table of contents page Administrative content — journal masthead, notices, indexes, etc. | ||