THE GENUS AUROCOCCUS 181 



conditions, and was generally absent in cultures from dust 

 and from the normal mouth. Proscher (1903) records 

 the same distinction, pyogenic cocci in general being 

 agglutinated by the serum of immunized goats, while 

 staphylococci from the air and the surfaces of the normal 

 body were not. 



Kutscher and Konrich (1904), also, found that patho- 

 genic staphylococci and those from other sources than 

 disease processes could be distinguished in a general 

 way by their reactions to immune sera, altho individual 

 cultures offered notable exceptions. Pathogenic forms 

 almost always formed hemolysins, while saprophytic 

 forms, as a rule, did not. These results have been con- 

 firmed by Veiel (1904), Fraenkel and Baumann (1905), 

 and many other observers. The qualities of Virulence are 

 of course among the most unstable of bacterial characters ; 

 and immunity reactions of all sorts are quickly modified 

 by the conditions of cultivation. Kayser (1902) and 

 other observers have shown, for example, that cultiva- 

 tion of pyogenic cocci in sugar media leads to a more 

 rapid decrease in virulence and hemolytic power than 

 that which occurs in ordinary broth. It is of interest to 

 note, in this connection, that Loeb found the presence of 

 sugar inimical to the production of peptonizing ferments 

 by the aurococcus (Neisser and Lipstein, 1903). In spite 

 of the instability of these characters there can, however, be 

 little doubt of the fact that pathogenic staphylococci of 

 both the orange and the white types, when freshly isolated, 



