134 PRACTICAL METHODS IN IMMUNITY. 



bacteria per c.c., we throw in 10 billion bacteria in a volume equal to 

 50 c.c. Then each c.c. of the 50 c.c. in the bottle would contain 

 10,000,000,000 divided by 50 or 200 million in each c.c. If we only 

 want a vaccine containing 100 million per c.c.. we should only add i c.c. 

 We now add 1/4% of Trikresol to the vaccine in order to insure ster- 

 ility. (Introduced with syringe, inserting needle through rubber cap.) 

 The syringe is best sterilized by drawing up vaselin or olive oil heated 

 to 150 C., and the neck and rubber cap of the bottle in boiling water. 

 We now draw up the desired dose of bacteria. If glass syringes are used, 

 simply boiling in water suffices. The ordinary doses are: For gono- 

 cocci, streptococci, pneumococci and colon vaccines 5 million to 50 

 million. For staphylococci 200 million to one billion. 



