152 PATHOGENIC ORGANISMS 



sufferers in the epidemic and from the probable original case. 

 These organisms were of the Str. pyogenes type and fermented 

 salicin but not raffinose or mannite. 



Another link in the chain of evidence in favour of the 

 streptococcal origin of these outbreaks, was founded by Jack- 

 son, 4 who showed that experimental arthritis could be pro- 

 duced in rabbits by the intravenous injection of hsemolytic 

 streptococci. This is important on account of the frequency of 

 joint infection as a sequel to septic sore throat as noted by 

 many observers in the various epidemics. 



Davis and Capps 5 endeavoured to produce an experimental 

 infection of milk by smearing the uninjured teats of a cow with 

 typical haemolytic streptococci recently isolated from a ease of 

 streptococcal tonsilitis; this was unsuccessful, but on repeating 

 the experiment after previously abrading the end of the teat 

 near the meatus, an infection occurred and streptococci and 

 leucocytes were found in abundance in the milk of the infected 

 quarter. Similar results were produced by injecting the cul- 

 ture into the udder. 



In view of the strong evidence that milk-borne streptococci 

 were causative agents of septic sore throat it became imperative 

 that a study should be made of the streptococci which are 

 invariably found in milk, even though produced under the best 

 conditions, in order to ascertain if there were any relation be- 

 tween these facts. Heinemann 6 has shown that Str. lacticus 

 occurs constantly in milk and that the morphological and bio- 

 chemical characteristics of this organism on ordinary media 

 are identical with those of Str. pyogenes. Later 7 he found 

 that by repeated passage through rabbits, he was able to exalt 

 the virulence of Str. lacticus to such an extent that compara- 

 tively small doses were fatal. The lesions produced were very 

 similar to those produced in human beings by Str. pyogenes. 

 Miiller 8 found that milk streptococci and pathogenic strep- 

 tococci showed no material difference in their agglutination and 

 hsemolytic properties but differed widely in the rapidity with 

 which they coagulated milk. Heinemann in 1915 9 reported 



