PUS-PRODUCING MICROORGANISMS 83 



a temperature which will kill their disease-producing 

 properties and stop their multiplication, but will not 

 alter their peculiar chemical composition. The number 

 of bacteria are then counted by a special technique and 

 hypodermic injections are made of definite numbers. 

 The size of dose and rate of increase of number injected 

 are controlled by what is called the opsonic index. The 

 opsonins, as will be remembered, are substances in the 

 blood which make the bacteria suitable for ingestion by 

 the white cells of the blood or phagocytes. The opsonic 

 index is the relation of the ability of the patient's 

 white cells to ingest bacteria as compared with a 

 normal person's white cells. This latter is considered 1. 

 If a person is infected with the pus cocci it means 

 that his opsonic index is below 1, and we try to increase 

 it up to or beyond 1. 



Vaccine Treatment. The theory and practice of this 

 so-called "vaccine treatment" or treatment with killed 

 bacteria are beset with many difficulties, and must 

 be carried out by specialists. The dead cultures are 

 called vaccines or bacterins. Today bacterins made 

 from the patients' infecting organism are chiefly used, 

 but chemical houses are putting on the market what 

 are called stock bacterins. The most suitable disease 

 for treatment of this kind is furunculosis (boils). 



Streptococcus Pyogenes. The cocci which grow in 

 chains, streptococci, must now be considered. There 

 are many varieties, but the Streptococcus pyogenes 

 (the pus-producing streptococcus) is the only one 

 that need be considered. This organism gives rise 

 chiefly to the spreading inflammation such as ery- 

 sipelas, cellulitis, and septicemia. It may cause a 



