PROCEEDINGS 
OF THE 
National Academy 
OF Sciences 
OF THE 
UNITED STATES OF AMERICA 
VOLUME 5, 1919 
EDITORIAL BOARD 
Raymond Pearl, Chairman Edwin B. Wilson, Managing Editor 
C. G. Abbot, Home Secretary George E. Hale, Foreign Secretary 
J. M. Clarke H. S. Jennings E. H. Moore 
H. H. Donaldson Jacques Loeb A. A. Noyes 
E. B. Frost Graham Lusk W. A. Noyes 
R. A. Harper A. G. Mayor E. L. Thorndike 
LuDViG Hektoen R. a. Millikan W. M. Wheeler 
Publication Office: Williams & Wilkins Company, Baltimore^ 
Editorial Office: Massachusetts Institute of Technology, Cambridge 
Home Office of the Academy: Washington, D. C. 
