l86 RELATIONSHIPS OF THE COCCACEyE 



2. AUR. AURANTIACUS (Schroter, Cohn) Winslow. A 

 parasitic coccus, living normally on the surfaces of the 

 human or animal body, or in diseased tissues. Occurs singly, 

 or in pairs, or irregular groups, rarely in short chains. 

 Generally stains by Gram. Meager to good surface growth, 

 of orange color. Acid production moderate in dextrose 

 broth, but slight in lactose broth. Nitrates not reduced. 

 Growth better at 37 degrees, but pigment production better 

 at 20 degrees. Gelatin not liquefied. 



The third type, among the aurococci, differs from 

 Aur. aureus by possessing the power of nitrate reduction, 

 and by other tendencies which ally it to a certain extent 

 with the saprophytic Metacoccaceae. Thirty-five cultures, 

 out of our series of one hundred and eighty, showed the 

 power of reducing nitrates and may be classed with this 

 type. There was an important difference in the end prod- 

 uct of the action of various strains. Ten cultures gave 

 positive tests for both nitrites and ammonia in a large 

 proportion of the tubes tested (ten in number for each 

 culture). Ten of the strains showed ammonia but not 

 nitrites, / and fifteen strains showed nitrites but no 

 ammonia. It was thought at first that this difference 

 might be due to the fact that different strains carried out, 

 more or less completely, a reduction, first from nitrates 

 to nitrites and then from nitrites to ammonia. A special 

 study was made of this point, by inoculating a series of 

 tubes with certain selected cultures and examining one tube 

 a day for two weeks, and by inoculating large flasks of 



