INFORMATION TO CONTRIBUTORS 
The Proceedings is the official organ of the Nationai, Academy op 
Sciences and of the Nationai. Research Counch. for the publication of 
brief accounts of important current researches of members of the Academy 
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and wide circulation of the results of American research among investi- 
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Articles should be brief. The viewpoint should be comprehensive 
in giving the relation of the paper to previous publications of the author 
or of others and in exhibiting, where practicable, the significance of the 
work for other branches of science. Elaborate technical details of the 
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International Catalogue of Scientific Literature, viz., name of author, 
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of Journal, with place of publication, series (if any), volume, year, inclusive 
pages. For example: Montgomery, T. H., J. Morph,, Boston, 22, 1911 
(731-815); or, Wheeler. W. M., Konigshutg, Schr. physik, Ges., 55, 1914 
(1-142). 
Papers by members of the Academy may be sent to Edwin Bidwell 
Wilson, Managing Editor, Mass. Institute of Technology, Cambridge, 
Mass. Papers by non-members should be submitted through some 
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Copyright » 1920, by the National Academy Sciences 
