This journal provides immediate access to some articles. Volume 30(12); December 15, 1944 Botany Visible Expression of Cytoplasmic Pattern in the Differentiation of Xylem Strands PMCID: PMC1078734 Genetics The Synapsis of the Sex Chromosomes of Drosophila Miranda in Relation to Their Directed Segregation PMCID: PMC1078733 Pathology and Bacteriology A Growth-Delaying Effect of Ultraviolet Radiation PMCID: PMC1078735 Incidence of Metabolic Changes among Virus-Resistant Mutants of a Bacterial Strain PMCID: PMC1078736 X-Ray Induced Growth Factor Requirements in Bacteria PMCID: PMC1078737 Physics On the Theory of the Tension of an Elastic Cylinder PMCID: PMC1078732 Physiology and Biochemistry The Mechanics of Bioluminescence PMCID: PMC1078731 Journal Matter Administrative content — journal masthead, notices, indexes, etc. | ||