TREASURY DEPARTMENT. 
Public Health and Marine-Hospital Ser\4ce of the United States. 
Waxter Wyaxax, Stirgeon-General. 
HYGIENIC LABORATORY.— BULLETIN No. 12. 
March, 1903. 
THE BACTERIOLOGICAL IMPURITIES 
OF 
VACCTXE VIRUS. 
AN EXPERIMENTAL STUDY. 
BY 
M. J. ROSEXAU, 
DIRECTOR OF HYGIEXIC LABORATORY. 
WASHINGTON : 
GOVERNMENT PRINTING OFFICE. 
1903- 
