VOLUME S FEBRUARY, 1919 
NUMBER 2 
1 
PROCEEDINGS 
! 
OF THE 
National Academy 
OF Sciences 
OF THE 
UNITED STATES OF AMERICA 
EDITORIAL BOARD 
Raymond Pearl, Chairman Edwin B. Wilson, Managing Editor 
C. 0. Abbot, Acting Home Secretary George E. Hale, Foreign Secretary 
i 
J. M. Clarke 
H. H. Donaldson 
E. B. Frost 
R. A. Harper 
LuDViG Hektoen 
H. S. Jennings 
Jacques Loeb 
Graham Lusk 
A. G. Mayor 
R. A. MiLLIKAN 
E. H. >t00RE 
A. A. No YES 
W. A. NOYES 
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. 
Eatertd Mseodnd-cIa« matter &t the postoffice at Baltimore. Maryland .under the act of August, 24. 1912. Acceptance (or mailiof At special 
rate of posta^ provided for in SeoJibn 1103, Act of October 3, 1917. Autfconzcd on July 3, 1918. 
Price per annum, $5.00 
