Page:Popular Science Monthly Volume 91.djvu/824

This page needs to be proofread.

How New York City's Health Department Makes

���Preparing the Bacteria

In the preparation of typhoid vaccine the bacteria are grown in the bottles you see on the table. The germs are killed by pouring a salt solution over them. The bottle on the shelf contains the salt solu- tion which is being si- phoned into the bottle containing the colony of typhoid fever germs

��Transferring the Bacilli Tetanus bacilli occur in dust, earth and manure. They do not grow in the presence of oxygen and are particularly dangerous if they get into deep wounds. The young lady in the photograph is drawing up tetanus bacilli from the bottom of a test tube by means of a tube which she - holds in her mouth. Thus the germs are transferred from tube to tube

��The Resultant Powerful Toxin

Here the large flask is being inoculated with tetanus bacilli. The small wire basket at the right contains test tubes in which are the tetanus germs. The flame which you see just to the right of the flask which is being inoculated is kept burning so that any instrument may be immediately sterilized after exposure

��The Final Step

The finished product containing millions of dead typhoid fever ba- cilli is poured by I of a siphon into large bottles. The vaccine is kept in a refrigerator until it is needed for use. Note the milky appear- ance of the vaccine

��� �