Voi,. 9 December 4, 19 19 No. 20 



JOURNAL 



OF THE 



WASHINGTON ACADEMY 

 OF SCIENCES 



BOARD OF EDITORS 



A. S. Hitchcock J. Franki,in Meyer R. B. Sosman 



BDRSAD OP PLANT IMDUSTKy BDRBAU OP 8TANDAKD8 CBOPHTSICAI. LABOSATOBT 



ASSOCIATE EDITORS 



H. V. Hari^an Sidney Paige 



BOTANICAL SOCIBTT OBOLOOICAI. SOCIBTT 



N. HOLUSTER S. A. ROHWBR 



BIOLOGICAL SOCIBTV BNTOMOLOGICAL SOCIBTT 



E. C. McKelvy F. B. SilsbEE 



CBBmCAL SOCIBTV PHILOSOPHICAL SOCIBTV 



J. R. SWANTON 



ANTHROPOLOGICAL SOCIBTV 



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Entered aa Second Class Matter, January 25, 1919, at the post>ofBce at Easton. Pa., under the 

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