VOLUME 5 OCTOBER, 1919 NUMBER 10 
PROCEEDINGS 
OF THE 
National Academy 
OF Sciences 
OF THE 
UNITED STATES OF AMERICA 
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. Millikant W. M. Wheeler 
Publication Office: Williams & Wilkins Company, Baltimore 
Editorial Office: Massachusetts Institute of Technology, Cambridge 
Home Office of the Academy: Washington, D. C. 
Entered as second-class matter at the postoffice at Baltimore, Maryland, under the act of August 24, 1912. Acceptance for mailing at special 
rate of postage provided for in Section 1 103, Act of October 3, 191 7. Authorized on July 3, 1918. 
Price per annum, $5.00 
