0 0 6 ' AO 
/ 
PROCEEDINGS 
OF THE 
National Academy 
of Sciences 
OF THE UNITED STATES OF AMERICA 
VOLUME 4, 1918 
if \ A 
EDITORIAL BOARD 
Raymond Pearl, Chairman Edwin B. Wilson, Managing Editor 
Arthur L. Day, Home Secretary 
George E. Hale, Foreign Secretary 
J. J. Abel 
J. M. Clarke 
H. H. Donaldson 
E. B. Frost 
R. A. Harper 
J. P. Iddings 
Jacques Loeb 
Graham Lusk 
A. G. Mayor 
R. A. Millikan 
E. H. Moore 
A. A. No yes 
Alexander Smith 
E. L. Thorndike 
W. M. Wheeler 
Publication Office: Williams & Wilkins Company, Baltimore 
Editorial Office: Massachusetts Institute of Technology, Cambridge 
Home Office of the Academy : Washington, D. C. 
