f 



PATHOGENIC BACTERIA. 247 



be coagulated. The growths are never very luxuriant, and 

 may die out entirely after a few transplantations. 



It is killed by exposure to 52 to 54 C, in ten minutes. 

 The streptococcus pyogenes occurs frequently on the mu- 

 cous surfaces of the healthy body. It is often found in 

 pus, especially pus of spreading inflammations of the kind 



FIG. 57. 



Streptococcus pyogenes, from a Pure Culture. (X 1000.) 



known as cellulitis. This organism is the commonest infec- 

 tious agent in puerperal fever, metritis and peritonitis. It 

 occurs commonly in inflammations of the serous membranes 

 pleuritis, pericarditis and peritonitis. It has been dis- 

 covered many times in ulcerative endocarditis, and in 

 broncho-pneumonia. It is frequently present in the false 

 membrane found in genuine diphtheria. It is also the cause 

 of many of the pseudo-membranous or so-called " diph- 

 theritic " affections of the throat where the Klebs-Loffler 

 bacillus of diphtheria is wanting. These cases may be in- 

 distinguishable clinically from genuine diphtheria, and their 



