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I VOLUME 6 APRIL, 1920 NUMBER 4 | 
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1 PROCEEDINGS 1 
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I OF THE 1 
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f National Academy | 
I OF Sciences 1 
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1 OF THE m 
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I UNITED STATES OF AMERICA I 
EDITORIAL BOARD 
Raymond Peari^, Chairman Edwin B. Wilson, Managing Editor 
C. G. Abbot, Home Secretary George E. Hale, Foreign Secretary 
J. M. Clarke 
A. L. Day 
Gano Dunn 
E. B. Frost 
LUDVIG Hektoen 
L. J. Henderson 
H. S. Jennings 
Jacques Loeb 
J. C. Merriam 
R. A. Millikan 
E. H. Moore 
W. A. NoYES 
W. J. V. OSTERHOUT 
E. L. Thorndike 
W. M. Wheeler 
Publication Ofl&ce : Eschenbach Printing Company, Easton, Pa. 
Editorial Office: Massachusetts Institute of Technology, Cambridge 
Home Office of the Academy: Washington, D. C. 
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Application pending for entry as second-class matter 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 on July 3, 1918. 
Price per annum, $5.00 
