THE GENUS AUROCOCCUS 189 



chains. Reaction to Gram stain variable, more often positive 

 than not. Good to abundant surface growth, of orange color. 

 Acid production moderate in dextrose and lactose broth. 

 Nitrates reduced to ammonia, or nitrites, or both. Growth 

 generally equal at 20 and 37 degrees; pigment production 

 equal, or better at 20 degrees. Gelatin usually liquefied 

 rapidly; rarely, not liquefied. 



These three species are the only ones which seem clearly 

 established in the light of present knowledge. The work 

 on immunity reactions, which has previously been re- 

 viewed, makes it clear that a group of aurococci exists 

 which differs from the common pyogenic Aur. aureus in 

 lacking hemolytic power, and in failing to agglutinate 

 with immune sera. These differences in pathogenic prop- 

 erties have not so far been correlated with a proper study 

 of biochemical characters. The non-pathogenic forms 

 may correspond with Aur. aurantiacus or with Aur. 

 mottis or with a new type resembling Aur. aureus, except in 

 virulence. Without further study of these points it seems 

 unwise to complicate matters by the introduction of a 

 new specific name, based solely on low hemolytic power 

 and failure to agglutinate. Comparative work on serum 

 reactions and biochemical characters should be fruitful 

 here. 



The orange cocci occasionally found in water or in 

 earth, like those which occur even more commonly in air, 

 are apparently stray parasitic forms which have persisted 

 in an unnatural environment, perhaps with the loss of 



