U. S. DEPARTMENT OF AGRICULTURE. 



BUREAU OF PLANT INDUSTRY— BULLETIN NO. 189. 



B. T. GALLOWAY, Chief of Bureau. 



THE SOURCE OF THE DRUG DIOSCOREA, WITH A 



CONSIDERATION OF THE DIOSCOREil 



FOUND IN THE UNITED STATES. 



BY 



HARLEY HARRIS BARTLETT, 

 Chemical Biologist, Drug-Plant Investigations. 



Issued November 11, 1910. 



WASHINGTON: 

 government printing office. 



1910. 



