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Volume 25(2);  February 1939
The cover of the journal
Astronomy
Astrophysical Consequences of Metastable Levels in Hydrogen and Helium
O. Struve, K. Wurm, and L. G. Henyey
Proc Natl Acad Sci U S A. 1939 February; 25(2): 67–73.
PMCID: PMC1077713
Botany
Growth and Differentiation in Living Plant Meristems
Edmund W. Sinnott
Proc Natl Acad Sci U S A. 1939 February; 25(2): 55–58.
PMCID: PMC1077711
Geology and Paleontology
The Oxidation-Reduction Potentials of Lake Waters and Their Ecological Significance
G. E. Hutchinson, E. S. Deevey, Jr., and Anne Wollack
Proc Natl Acad Sci U S A. 1939 February; 25(2): 87–90.
PMCID: PMC1077717
Mathematics
On Ideals of Differential Polynomials
J. F. Ritt
Proc Natl Acad Sci U S A. 1939 February; 25(2): 90–91.
PMCID: PMC1077718
Generalizations to Space of the Cauchy and Morera Theorems
Maxwell Reade and E. F. Beckenbach
Proc Natl Acad Sci U S A. 1939 February; 25(2): 92–97.
PMCID: PMC1077719
An Equivalence Theorem for Series of Orthogonal Polynomials
G. H. Peebles
Proc Natl Acad Sci U S A. 1939 February; 25(2): 97–104.
PMCID: PMC1077720
Curvature Element Transformations Which Preserve Integrable Fields
Edward Kasner and John De Cicco
Proc Natl Acad Sci U S A. 1939 February; 25(2): 104–111.
PMCID: PMC1077721
Physics
Expressions for the Current in the Bloch Approximation of “Tight Binding” for Metallic Electrons
J. Bardeen and J. H. Van Vleck
Proc Natl Acad Sci U S A. 1939 February; 25(2): 82–86.
PMCID: PMC1077716
Physiology and Biochemistry
Temperature and the Critical Intensity for Response to Visual Flicker: II
W. J. Crozier
Proc Natl Acad Sci U S A. 1939 February; 25(2): 78–82.
PMCID: PMC1077715
Psychology and Anthropology
Quantitative Analysis of the Interaction of Individuals
Eliot D. Chapple
Proc Natl Acad Sci U S A. 1939 February; 25(2): 58–67.
PMCID: PMC1077712
The Resolution of Six Tests into Three General Factors
Edwin B. Wilson and Jane Worcester
Proc Natl Acad Sci U S A. 1939 February; 25(2): 73–77.
PMCID: PMC1077714
Journal Matter
Administrative content — journal masthead, notices, indexes, etc.
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