336 



PATHOGENIC OKGANISMS 



Pure cultures of streptococci were first obtained by Fehleisen' in 1883 

 and by Rosenbach^ in 1884. The thorough and systematic researches of 

 the last-named authors, together with those of Passet,^ were of special 



Fig. 72. — Streptococcus pyogenes. 



influence in placing our knowledge of the pathogenic properties of 

 streptococci upon a scientific basis. 



Morphology and Staining. — ^The individual streptococcus is a spherical 

 microorganism measuring from 0.5 micron to 1 micron in diameter. 

 Since the line of cleavage of cocci, when in chains, is perpendicular to the 



'Fehldsen, " Aetiol. d. Erysipelas," Berlin, 1883. 



2 Bosenbach, " Mikroorg. bei Wundinfektion,'' etc., Wiesbaden, 1884. 



^Passet, " Untersuch. uber die eitrigen Phlegm.," etc., Berlin, 1885. 



