276 STREPTOCOCCUS-PNEUMOCOCCUS GROUP 



tory animals. Subcutaneous injections of morbid material into 

 rabbits result variously, depending upon the virulence of the strain 

 for this animal (not necessarily upon its virulence for man) ; a localized 

 abscess may form or an erysipelatoid inflammation may occur, which 

 is usually somewhat localized, but may develop into a wide-spread 

 cellulitis. Intraperitoneal injections are usually followed by rapidly- 

 fatal peritonitis. Death may occur within twenty-four hours. Intra- 

 venous injections may cause a rapidly fatal generalized septicemia, or, 

 if the strain is less virulent and death does not occur during the first 

 three to four days, the serous surfaces may be violently inflamed. Less 

 virulent strains which do not cause acute death usually lead to endo- 

 cardial or joint involvement. Mice are nearly as susceptible to strepto- 



FIG. 35. Streptococci in liver, section stained by Gram's method. X 800. (KoJle and 



Hetsch.) 



coccus infection as rabbits. Guinea-pigs are less susceptible; subcu- 

 taneous inoculations usually lead to abscess formation, which soon 

 heals, but intraperitoneal injections may result in peritonitis and 

 death. Horses are quite susceptible to infection with streptococci, 

 particularly with Streptococcus equi (Streptococcus coryzse contagiosae 

 equorum), which causes equine distemper or strangles. The udders of 

 milch cattle occasionally become infected with streptococci result- 

 ing in a severe inflammation, mastitis or garget, which may lead to 

 loss of function of one or more quarters of the udder. It is probable 

 from the investigations of Smith and Brown 1 that streptococci of 

 bovine origin are not commonly the etiological agents of septic sore 

 throat in man. 



1 Loc. cit. 



