480 BACTERIOLOGY. 



remaining for days or weeks. A granular deposit 

 appears at the bottom of the tube. 



The development in a mixture of ascitic fluid and 

 bouillon, which is the best medium for the growth of 

 the streptococcus, is more abundant than in bouillon. 

 The liquid is clouded, and a precipitate only occurs 

 after some days, the fluid gradually clearing. 



Growth on Solidified Blood-serum. This is also an 

 excellent medium for the streptococcus. Tiny, grayish 

 colonies appear twelve to eighteen hours after inocu- 

 lation. 



Growth in Milk. All streptococci grow well in milk. 

 As a rule, coagulation of the casein occurs with the 

 production of acid, but this is not always the case. 



The Duration of the Life of Streptococci Outside of 

 the Body. This is not, as a rule, very great. When 

 dried in blood or pus, however, they may live for 

 several months at room-temperature, and longer in an 

 ice-chest; and in gelatin and agar cultures they live 

 for from one week to three months; in bouillon cult- 

 ures they are usually short-lived, the majority dying 

 within two or three days, and very few living over a 

 month; but in serum bouillon they live much longer. 

 In order to keep streptococci alive and virulent, it is 

 best to keep them in serum or ascitic fluid bouillon in 

 small, sealed glass tubes in the ice-chest. The thermal 

 death-point of the streptococcus, according to Stern- 

 berg, is between 52 and 54 C., the time of exposure 

 being ten minutes. 



Von Lingelsheim has reported the following results 

 obtained in an extended series of experiments made to 

 determine the germicidal power of various chemical 

 agents as tested upon this micro-organism (time of ex- 



