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A Journal of General Botany 



VOLUME 21 

 NUMBER 9 



SEPTEMBER, 1918 



CONTAINING 



Root Habit and Plant Distribution in the Far North. Howard E. Pulling. 223 



A Promising Chemical Photometer for Plant Physiological Research. 

 Charles S. Ridgwa}' 234 



Books and Current Literature 241 



Notes and Comment 244 



PUBLISHED MONTHLY 



OFFICE OF PUBLICATION 



2419-21 Greenmount Ave. 



baltimore, md. 



EDITORIAL OFFICE 



TUCSON, ARIZONA 



Entered as second-class matter March 9, 1912, at the post office at Baltimore, Maryland, under the act of July 10, 1894 



