246 MANUAL OF BACTERIOLOGY. 



monly in inflammations of the serous membranes — pleuritis, 

 pericarditis and peritonitis. It has been discovered many 

 times in ulcerative endocarditis and in bronchopneumonia. It 

 is frequently present in the false membrane found in genuine 

 diphtheria. It is also the cause of many of the pseudomem- 

 branous or so-called "diphtheritic" affections of the throat 

 where the Klebs-Loffler bacillus of diphtheria is viranting. 

 These cases may be indistinguishable clinically from genuine 





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Fig. 63. — Streptococcus Pyogenes in Pus, Gram's Stain. (X 1000.) 



diphtheria, and their nature can be revealed only by bacterio- 

 logical examination. They are, however, as a rule, milder than 

 genuine diphtheria. The pseudomembranous affections of the 

 throat which occur in scarlet fever and measles are generally 

 caused by the Streptococcus pyogenes, although those diseases 

 may be complicated by genuine diphtheria. Streptococci are 

 very commonly present in the throat in scarlet fever,* and some- 

 times occur in the blood. Some observers believe that scarlet 



* Weaver. American Medicine. April 18, 1903. 



