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VOLUMES APRIL, 1922 NUMBER 4 1 
PROCEEDINGS | 
' OF THE I 
National Academy | 
OF Sciences | 
OF THE 1 
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i UNITED states OF AMERICA I 
I EXECUTIVE COMMITTEE 
I Edwin BrowELL Wilson, Managing Editor 
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I Raymond Pbarl Vbrnon Kmujoqg 
PUBLISHED MONTHLY 
Publication Office: Eschenbach Printing Company, Easton, Pa. 
I Editorial Office: Massachusetts Institute of Technology, Cambridge 
Home Office of the Academy: Washington, D. C. 
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Bntered as second-clasa matter June 21, 1920. at the postoffice at Easton, Pennsylvania, under the act of August 24. 1912. 
Acceptance for mailing at special rate of postage provided for in section 1103, Act of October 3, 1917. Authorized June 18, 1920 
Price per annum, $5.00 
