llllllllllllllllilllllllilllllllllllilllllllllllililllllllH^ 
VOLUME 6 
FEBRUARY, 1920 
NUMBER 2 
PROCEEDINGS 
OF THE 
I 
National Academy 
OF Sciences 
> • OF THE 
UNITED STATES OF AMERICA 
i 
I 
EDITORIAL BOARD 
Raymond Peari., CtoVmaw UBwm B.Wii^soi^, Managing Editor 
C. G. Abbot, Home Secretary Gkorge E. Hai^e, Foreign Secretary 
I 
I 
J. M. Clarke 
A. L. Day 
Gano Dunn 
E. B. Frost 
LuDviG Hektokn 
L. J. Henderson 
H. S. Jennings 
Jacques Loeb 
J. C. Merriam 
R. A. M11.WKAN 
E. H. Moore 
W. A. NoYES 
W. J. V. OSTERHOUT 
E. L. Thorndike 
W. M. WHEEI.ER 
Publication Office: Eschenbach Printing Company, Eastou, Pa, 
Editorial Office : Massachusetts Institute of Technology, Cambridge 
Home Office of the Academy: Washington, D, C, 
illlillllillllllliillliillllllllillllilllllllllllllilliliiiiillili^ 
Application pending for entry as second-class matter at the postofifice at Baston, Pennsylvania, 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, 1*^17. Authorized on J<xly 3, 191 S. 
Price per annum, $5.00 
