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VOJvUMK () 
NOVEMBER, 1920 
PROCEEDINGS 
OF THE 
NUMBER 11 
National Academy 
OF Sciences 
OF THE 
UNITED STATES OF AMERICA 
EDITOklAL BOARD 
Raymond Peari,, Chairman Edwin B. Wilson, Managing Editor 
C. G. Abbot, Home Secretary George E. Hai^E, Foreign Secretary 
J. M. Clarke 
A. L. Day 
Gano Dunn 
E. B. Frost 
lyUDVIG^EKTOEN 
L. J. Henderson 
H. S. Jennings 
Jacques Loeb 
J. C. Merriam 
R. A. MiLUKAN 
PUBLISHED MONTHLY 
E. H. Moore 
W. A. NoYES 
W. J. V. Osterhout 
E. L. Thorndike 
W. M. Wheeler 
i Publication Office : Eschenbach Printing Company, Easton, Pa. 1 
1 Editorial Office : Massachusetts Institute of Technology, Cambridge 1 
8 Home Office of the Academy: Washington, D. C. j 
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Untered as second-class matter June 21, 1920, at the postoflBce at Easton, Pennsylvania, under the act of Aujfvist 24, 1912, 
Acceptaooe 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 
