CLASSIFICATION 29 



guisli it from others. However, such deficiencies cannot well 

 be avoided in the time of rapid accumulation of observations 

 and the evolution of methods. 



§ 19. Classification of streptococci, A few investi- 

 gators have tried to eliminate the confusion concerning species 

 by classifying streptococci according to distinct morphologic 

 characters and pathogenic properties. Of these classifications 

 the following may be mentioned : 



I. The classification of von Lingelshei^n. This author di- 

 vides all streptococci into two groups, or species, namely : — 



(a) Streptococcus brevis — which is non-pathogenic. 

 ((^) Streptococcus longus — which is pathogenic. 



This is a combination of pathogenesis and morphology 

 which the author thought applicable to the entire genus. He 

 worked very largely, however, with the streptococci from the 

 human mouth and throat. 



II. The classification of Kiwth. Kurth worked largely 

 with the streptococci from cases of scarlatina. His system is 

 practically the same as that of von Lingelsheim, with the ex- 

 ception that he does not include pathogenesis as necessarily 

 belonging to either group. The divisions are as follows : 



ia) Streptococcus rigidi — Streptococci growing in short 

 chains, and which impart a uniform turbidity to bouillon. 



(b) Streptococcus flexuosi — Streptococci which grow in long 

 interlacing chains which form flocculi in bouillon leaving the 

 liquid clear. 



III. The classification of Pasquale . Pasquale worked with 

 thirty-three streptococci, including nearly all of the then known 

 species. His work was quite exhaustive, but he had to deal 

 wnth cultures of various generations. He divides them into 

 four groups, as follows : 



{a) Short saphrophytic streptococci. 



i^b) Long non- virulent streptococci. 



(£■) I^fOng pathogenic streptococci. 



(flf) Short highly infectious streptococci. 



Group (yd) pertains largely to bacteria which are no longer 

 recognized as streptococci, for example, the diplococcus (yl//<:r£'- 

 coccus lanceolatus) of pneumonia. It is now known that strep- 



