TREASURY DEPARTMEiNT. 
Public Health and Marine-Hospital Service of the United States. 
Walter Wyman, Surgeon-General. 
HYGIENIC LABORATORY-BULLETIN No. 20. 
ROSE^jMAU, Director. 
April, 1905. 
A ZOOLOGICAL INVESTIGATION 
INTO 
THE CAUSE, TRANSMISSION, AND SOURCE 
OF 
ROCKY MOUNTAIN “SPOTTED FEVER.” 
BY 
i 
CH. WARDKLL SXILKS. 
WASHINGTON: 
GOVERNMENT PRINTING OFFICE. 
1905. 
