These charts were originally issued in 1961 as an unnumbered publi- 
cation by the Laboratory Branch of the Communicable Disease Center 
for use in training courses. 
Public Health Service Publication No. 1234 
April 1965 
U.S. Government Printing Office, Washington: 1965 
For sale by the Superintendent of Documents, U.S. Government Printing Office 
Washington, D.C., 20402 - Price 20 cents 
