THE GENUS STREPTOCOCCUS 169 



ter, Str. Fischeli, Chester, Str. carnis, Chester). Escherich 

 (1886) described a form which liquefied quite actively, 

 under the name of Str. coli gracilis. It was character- 

 ized by the very small size of the cells; it failed to coagu- 

 late milk and did not liquefy blood serum. To illustrate 

 the confusion which has arisen from trinomials, it may 

 be noted that this organism was called Str. gracilis by 

 Lehmann and Neumann (1896), and Str. coli by Chester 

 (1901). Str. septicus (Babes) , Chester, and Str. lique- 

 faciens, Sternberg, are closely related forms. An inter- 

 esting streptococcus, described by MacCallum and 

 Hastings (1899) as Micrococcus zy mo genes, showed the 

 same characteristics as Str. gracilis (small size, liquefac- 

 tion of gelatin), and in addition liquefied serum slightly, 

 and after coagulating milk subsequently liquefied the 

 clot. Birge (1905) later isolated the same organism. 

 He was able to show that the coagulation of milk by this 

 form was, in part at least, due to the production of a 

 coagulating enzyme. A similar streptococcus was found 

 by Harrevelt in decaying meat and was named Str. carnis 

 by Chester (1901). 



The first actively liquefying streptococcus described 

 appears to be Str. coli gracilis; and this species may be 

 taken as the type center of the liquefying streptococci. 

 M. zymogenes is apparently an extreme form of the same 

 group. A streptococcus of this sort, studied by Gordon 

 (1905), acted on salicin and mannite tho not on raffinose 

 and inulin; and the same fermentative power was found 



