DIPLOCOCCUS PNEUMONIAE (FHANKEL) 67 



media, cerebro-spinal meningitis, and many other 

 diseases. 



The cultures are both infective and toxic. Sus- 

 ceptible animals can be protected against the viru- 

 lent organism, but this protection is not generally 

 considered to extend to the toxins. Protection is 

 afforded by the blood serum of immunised animals, 

 or of convalescents from pneumonia (Klemperer). 



As found in the saliva, in the sputum of pneumonic 

 patients, in pneumonic lungs and in the blood, pleural 

 and peritoneal exudations of inoculated animals the 

 organism appears as a minute diplococcus about 5 /* 

 to 1 n in diameter (Fig. 62) surrounded by a well- 

 marked capsule. The individual cells are elongated 

 and hastate in shape, and are placed with their broad 

 bases in apposition when united as diplococci. This 

 is the typical form, but variations from it are very 

 common and many cells are simply spherical. 



The organism is stained by Gram's method. 



Between the temperatures 22° C and 42° C. the 

 microbe can be cultivated, but unless special pre- 

 cautions are taken the cultures are scanty, the 

 virulence rapidly lost, and the vitality persistent 

 for a short time only. On agar, which is much im- 

 proved as a culture medium by being covered with a 

 layer of blood, the culture (Fig. 63) occurs as a 



