252 MANUAL OF BACTERIOLOGY. 



lated. The colonies are seen in their characteristic form 

 upon agar, and are developed after about forty-eight hours, 

 appearing as minute, whitish, translucent, circular growths. 



It is killed by an exposure to 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 pneu- 



FIG. 61. 



I 



Pneumococcus of Frankel in sputum of pneumonia, Gram's stain and 

 eosin. (X 1000.) 



monia. Cultures need to be transplanted every few days; 

 they cannot usually be propagated more than a couple of 

 months. 



The virulence of the organism for animals diminishes 

 rapidly in cultures. In cultures it frequently grows as a 

 streptococcus. When virulent, it is pathogenic to mice and 

 rabbits, less so to guinea-pigs. In these animals it is likely 

 to lead to inflammations, and to rapidly fatal septicemia 

 (twenty-four to forty-eight hours). The blood may con- 

 tain great numbers of the diplococci. It may be introduced 



