112 RELATIONSHIPS OF THE COCCACE^E 



streptococcus type, lowered virulence, and the loss of 

 the inulin-fermenting power. This variability under 

 artificial conditions does not, however, alter the fact that 

 the properties mentioned are characteristic of the pneumo- 

 coccus as actually found in the body. 



Another important difference between streptococci and 

 diplococci, observed first by Schottmuller (1903), lies in 

 the fact that the former frequently exhibit hemolytic 

 power, while the latter do not. The most typical strains 

 of Str. pyogenes, when grown upon blood agar, form 

 grayish colonies surrounded by a clear zone from which 

 the hemoglobin has been entirely removed. This type 

 Schottmuller called Str. pyogenes sen erysipelatos. On 

 the other hand, D. pneumonia, the zooglcea-forming 

 diplococcus and certain streptococci (called by Schott- 

 muller Str. mitior sen mridans) , form in blood agar green- 

 ish colonies, without obvious solution of the hemoglobin. 

 In blood-broth, Str. pyogenes produces a carmine red 

 coloration, while organisms of the second type change the 

 solution to a brownish hue. Rosenow (1904) indepen- 

 dently observed this characteristic action of the pneumo- 

 cocci; and explained the brownish turbidity formed in 

 blood-broth as due to the action of the organism upon 

 the hemoglobin. 



That both the Hiss reaction and the Schottmuller 

 reaction are complex phenomena is indicated by some 

 recent work of Longcope's (1905). He finds that blood 

 sera may or may not contain in themselves substances 



