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 





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 throat 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. Injections Diseases. Vol. III., 1906. pp. 755-771- 

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

 ii 60. 



