VOLUME 20 

 NUMBER 1 

 JANUARY, 1917 



CONTAINING 



A Quarter-Century of Growth in Plant Physiology <- • - * ^' *-* '-^ "^ ^ 



Burton Edward Livingston 1 



Notes on the History of the Willows and Poplars 



Edward W, Berry 16 



Books and Current Literature 29 



Notes and Comment 32 



PUBLISHED MONTHLY 



OFFICE OF PUBLICATION 



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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 15, 1834 



