298 BACTERIA 



This latter fact gave support to the theory that streptococ- 

 cus reproduced itself by artkrosporeSj or " mother-cells." 



In culture upon the ordinary media streptococcus is com- 

 paratively slow-growing, producing minute white colonies 

 on or about the sixth day. It does not liquefy gelatine, 

 and remains strictly localised to the track of the inoculating 



Types of Streptococcus 



needle. Like the staphylococcus, it readily loses virulence. 

 The thermal death-point is, however, lower: 54° C. for ten 

 minutes. Marmorek has devised a method by which the 

 virulence may be greatly increased, and he holds that it de- 

 pends upon the degree of virulence possessed by any partic- 

 ular streptococcus as to what effects it will produce. By the 



