Vol. VII No. 20 



December 4, 1917 



JOURNAL 



OF THE 



WASHINGTON ACADEMY 



OF SCIENCES 



BOARD OF EDITORS 

 N. Ernest Doeset Adolph Knopf A. S. Hitchcock 



BUREAU Or STANDARDS GEOLOGICAL SURVET BUREAU OF PLANT INDUSTBY 



PUBLISHED SEMI-MONTHLY 

 EXCEPT IN JULY, AUGUST, AND SEPTEMBER, WHEN MONTHLY 



BT THE 



WASHINGTON ACADEMY OF SCIENCES 



OFFICE OF PUBLICATION 



WILLIAMS & WILKINS COMPANY 



BALTIMORE, MD. 



Entered a* eecond-clase matter July 14. 1911, at the poet office at Baltimore, Maryland, under the Act of 



July 10, 1894 



