158 PATHOGENIC BACTERIA. 



In gelatin puncture-cultures no liquefaction is observed. 

 The minute spherical colonies grow along the whole 

 needle-track and form a slightly opaque granular line. 



Upon agar-agar an exceedingly delicate transparent 

 growth develops slowly along the line of inoculation. 

 It consists of almost transparent, colorless small colo- 

 nies which do not become confluent. 



The growth upon blood-serum much resembles that 

 upon agar-agar. The streptococcus does not grow upon 

 potato. 



The organism seems to grow well in milk which is 

 coagulated and digested. 



The Streptococcus is not very sensitive to acids, and 

 can be grown quite well in media with a slightly acid 

 reaction. 



Sternberg found that the streptococci succumb to a 

 temperature of 52-54 C. continued for ten minutes. 



The streptococcus pyogenes is not very pathogenic for 

 animals. Subcutaneous injections into mice and rabbits 

 are, as a rule, without either general or local manifesta- 

 tions of importance. If, however, an ear of a rabbit is 

 inoculated with a small amount of a pure culture care- 

 fully scratched in, a small patch resembling erysipelas 

 usually results. The disturbance passes away in a few 

 days and the animal recovers. 



Like the staphylococci, the Streptococcus pyogenes is 

 frequently associated with internal diseases, and has been 

 found in ulcerative endocarditis and in the uterus in 

 bases of infective puerperal endometritis. Its relation 

 to diphtheria is of interest, for, while, in all probability, 

 the great majority of cases of pseudo-membranous angina 

 are caused by the Klebs-Loffler bacillus, yet an undoubted 

 number of cases are met with in which, as in Prudden's 

 24 cases, no diphtheria bacilli can be found, but which 

 seem to be caused by a streptococcus exactly resembling 

 that under consideration. 



There is no clinical difference in the picture of the 

 throat-lesion produced by the two organisms, and the 



