PATHOGENIC BACTERIA. 297 



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 wanting. 

 These cases may be indistinguishable clinically from genuine 

 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 



*% 



>*«,, 



'fiii.'i 



f 



Cl 



V 



4 



Fig. 68. — Streptococcus pyogenes in pus, Gram's stain. (X 1000.) 



generally caused by the Streptococcus pyogenes, although those 

 diseases may be complicated by genuine diphtheria. Strep- 

 tococci are very commonly present in the throat in scarlet 

 fever,* and sometimes occur in the blood. Ruedigerf using 

 blood agar found streptococcus present in the tlaroat in all the 

 cases of scarlatina — 75 cases — which he examined. HektoenJ 

 points out that while it is not yet established beyond question 



*Weaver. American Medicine. April 18, 1903. 

 \Journ. Infectious Diseases. Vol. III., 1906. pp. 755-771. 

 XJourn. Am. Med. Assn. Vol. XL VIII., No. 14, April 6, 1907. pp. 1158- 

 II 60. 



