STREPTOCOCCUS PYOGF1NES. 



165 



some of the individual members of a chain are larger than 

 the others. This is responsible for the belief that possibly 

 these larger cocci are arthrospores. The name streptococcus 

 conglomerate has been given to snarls of chains. 



Unlike the staphylococcus, the streptococcus is not grown 

 readily in culture. That is accounted for by the fact that it 

 is an exceedingly virulent germ, possessing but little vegeta- 

 tive power. In order to preserve the culture, frequent trans- 

 plantations are made, and this is always done at the expense 

 of the virulence of the coccus. It becomes considerably 

 attenuated, but the lost virulence can be regained by rapidly 



FIG. 68. 



FIG. 69. 



Streptococci in peritoneal fluid, partly Streptococci in throat exudate smeared 

 enclosed in leucocytes. X 1000. (Park.) on cover-glass. X 1000. (Park.) 



passing the coccus through rabbits until a very high degree 

 of toxicity is obtained (Fig. 70). Marmorek says that the 

 original virulence can be retained if a culture- medium 

 consisting of 3 parts of human blood-serum and 1 part of 

 bouillon is used, or ass ? milk, ascitic fluid, or the fluid from a 

 pleural effusion. The virulence of individual organisms is 

 apparently subject to marked variations. The requirements 

 as regards temperature are the same as those of the staphy- 

 lococcus. It is a facultative anaerobe. 



On gelatin plates the streptococcus forms very small, finely 

 granular, translucent colonies of a very light color. They 



