402 



PATHOGENIC MICROORGANISMS 



researches of the last-named authors, together with those of Passet, 5 

 were of special 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 



* 





FIG. 46. STREPTOCOCCUS PYOGE'NES. 



perpendicular to the long axis of the chain, adjacent cocci often 

 show slight flattening of the contiguous surfaces, forming, as it 

 were, a series of diplococci arranged end to end. As a general rule 

 the streptococci pathogenic for man, when grown upon favorable 

 media, have a tendency to form chains made up of at least eight 



6 Posset, "Untersuch. iiber die eitrigen Phlegm./' etc., Berlin, 1885. 





