TREASURY DEPARTMENT. 
Public Health and Marine-Hospital Service of the United States. 
Walter Wyman, Surgreon-General. 
HYGIENIC LABORATORY.-BULLETIN No. 20. 
j. 
April, 1905. 
Director. 
A ZOOLOGICAL IM'ESTIGATIOX 
INTO 
THE CAUSE, TRANSMISSION, AND SOURCE 
OF 
ROCKY MOUNTAIN "SPOTTED FEVER.” 
CH. WAlRDELL stiles. 
WASHINGTON: 
GOVER^^MEXT PRINTING OFFICE. 
1905. 
