304 MANUAL OF BACTERIOLOGY. 



with pneumococcus capsule staining and streptococcus cultural 

 features may with probability be diagnosed as pneumococcus 

 even though it does not return to the pneumococcus type after 

 animal passage. 



It is killed by an exposure to a moist temperature of 52° C. 

 for ten minutes. 



It is best cultivated from the blood of an animal which has 

 been infected with the sputum of a case of lobar pneumonia. 



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I 



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Fig. 71.— Pneumococcus of Frankel in sputum of pneumonia, Gram's 

 stain and eosin. 



Cultures need to be transplanted every few days'; they cannot 

 usually be propagated more than a month or twd months. 

 The virulence of the organism for animals diminishes rap- 

 idly in cultures. It frequently grows as a streptococcus on 

 artificial media. When virulent, it is pathogenic for mice and 

 rabbits; less so for guinea-pigs. In these animals it is likely 

 to lead to fatal septicemia in twenty-four to forty-eight hours* 

 when introduced subcutaneously or into the peritoneum or 

 when liquid cultures are injected intravenously. The blood 



