This journal provides immediate access to some articles. Volume 21(9); September 1935 Botany The Assimilation of Ammonium Nitrogen by Nitzchia Closterium and Other Marine Phytoplankton PMCID: PMC1076647 Mathematics Groups in Which the Squares Generate a Subgroup of Index Less Than Seven PMCID: PMC1076648 “Riemannian” Differential Geometry in Abstract Spaces PMCID: PMC1076649 Asymptotic Representations of Confluent Hypergeometric Functions PMCID: PMC1076650 Completely Integrable Differential Equations in Abstract Spaces PMCID: PMC1076651 An Unbiased Correlation Ratio Measure PMCID: PMC1076656 Physics A Refinement of the Heisenberg Theory of Ferromagnetism, Applicable to Simple Cubic Crystals PMCID: PMC1076652 Electrical Conductance of Short Gaps in Air PMCID: PMC1076653 Zoölogy and Anatomy The Color Changes in Uca Pugilator PMCID: PMC1076654 Processes of Localization in Developing Fundulus PMCID: PMC1076655 Journal Matter Administrative content — journal masthead, notices, indexes, etc. | ||