232 DISEASE CONTROL 



for an hour in a i per cent solution (273). The efficacy of penicillin 

 in protecting mice against streptococcal infections is brought out in 

 Table 42. 



TABLE 42. IN VIVO EFFICACY OF PENICILLIN COMPARED WITH SULFANILAMIDE 

 IN STREPTOCOCCUS HEMOLYTICUS INFECTIONS IN MICE 



From Robinson (752). 



Notes. Infection: 0.5 cc. of lO"* 6-hoiir-old culture dilution in broth. Treatment: Penicillin given sub- 

 cutaneously and sulfanilamide given orally immediately after the inoculation of bacteria, then every 

 3 hours day and night for 5 days. 



The effectiveness of penicillin has also been tested against various 

 other infections in experimental animals, with varying degrees of suc- 

 cess. It was found, for example, that the administration of penicillin in 

 relatively large doses to mice after injection with murine typhus rick- 

 ettsiae resulted in marked reduction in mortality, particularly when the 

 initial dosage of the rickettsiae was relatively small (614). 



Chemotherapeutic Action. Penicillin has also found an important 



