250 MANUAL OF BACTERIOLOGY. 



which also is useful in demonstrating the capsule. It is facul- 

 tatively anaerobic. It grows only at elevated temperatures, 

 preferably about 35° to 37" C. Gelatin is not hquefiied. It 

 grows well upon agar, upon "blood-serum and upon Guar- 

 nieri's medium (p. 69). It does not grow upon potato. Milk 

 usually becomes acid, and may or may not be coagulated. 

 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. 



/ 



^'% 



I 



I 



Fig. 66. — Pneumococcus of Frankel in Sputum on? Pneumonia, Gram's 

 Stain and Eosin. (X 1000.) 



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- 

 monia. Cultures need to be transplanted every few days; 

 they cannot usually be propagated more than a month or two 

 months. 



The virulence of the organism for animals diminishes rap- 

 idly in cultures. It frequently grows as a streptococcus on 



