LETTER OE TRANSMITTAL. 



U. S. Department of Agriculture, 



Bureau of Plant Industry, 



Office of the Chief, 

 Washington^ D. C 7 ., September i, 1908. 

 Sir : I have the honor to transmit herewith and to recommend for 

 publication as Bulletin Xo. 139 of the series of this Bureau the ac- 

 companying manuscript, entitled "American Medicinal Barks." 

 This paper was prepared by Miss Alice Henkel, Assistant in Drug- 

 Plant Investigations, and has been submitted by the Physiologist in 

 Charge with a view to its publication. 



Thirty-five drugs are fully described, and under many of the de- 

 scriptions briefer information concerning closely related species is 

 included. All of the w official " barks obtained from trees and shrubs 

 occurring in this country are described, as well as many " nonofficial " 

 ones. 



This bulletin forms the second installment on the subject of Ameri- 

 can medicinal plants, the first one treating of American root drugs, 

 and has been prepared to meet the steady demand for information 

 concerning the medicinal plants of this country. It is intended as a 

 guide and reference book for those who may be interested in the study 

 or collection of the medicinal plants found in the United States. 

 Respectfully, 



B. T. Galloway. 



Chief of Bateau. 

 Hon. James Wilson, 



Secretary of Agriculture. 



139 



