THE GENUS STREPTOCOCCUS 149 



named M. rheumaticus by Beaton and Walker (1903). 

 It was said to differ from typical Str. pyogenes in four 

 points, as follows : it changed the red color of blood-agar 

 to rusty brown, it grew well in filtrates from cultures of 

 ordinary pyogenic cocci, it grew in highly alkalin media, 

 and in such media produced considerable quantities of 

 acid. Inoculation of small doses into rabbits produced 

 acute arthritis. Walker and Ryffel (1903) state that this 

 organism, when grown in alkalin broth, produces a con- 

 siderable amount of formic acid, which they believe to 

 offer another differential test for separating it from Str. 

 pyogenes. The production of formic acid by this strep- 

 tococcus was considered by them as of special interest 

 in view of the presence of this acid in the urine of 

 rheumatic patients. Poynton (1904) later reported a new 

 isolation of M. rheumaticus, with successful animal inocu- 

 lations; and Beattie (1906), in a recent paper, strongly 

 maintains that the results obtained by injecting this form 

 into animals are very different from those which follow 

 the injection of Str. pyogenes. On the other hand, 

 Cole (1904) and others deny the validity of these con- 

 clusions and offer evidence that streptococci from vari- 

 ous sources produce, when inoculated into animals, the 

 symptoms held to be characteristic of M. rheumaticus. 

 Furthermore, in a long series of cases no organism could 

 be isolated by these observers from rheumatic lesions. 



With regard to smallpox, somewhat similar observa- 

 tions have been made, altho evidence is against the 



